Quantum Computing | D-Wave Systems

Quantum Computation

Rather than store information using bits represented by 0s or 1s as conventional digital computers do, quantum computers use quantum bits, or qubits, to encode information as 0s, 1s, or both at the same time. This superposition of statesalong with the other quantum mechanical phenomena of entanglement and tunnelingenables quantum computers to manipulate enormous combinations of states at once.

In nature, physical systems tend to evolve toward their lowest energy state: objects slide down hills, hot things cool down, and so on. This behavior also applies to quantum systems. To imagine this, think of a traveler looking for the best solution by finding the lowest valley in the energy landscape that represents the problem.

Classical algorithms seek the lowest valley by placing the traveler at some point in the landscape and allowing that traveler to move based on local variations. While it is generally most efficient to move downhill and avoid climbing hills that are too high, such classical algorithms are prone to leading the traveler into nearby valleys that may not be the global minimum. Numerous trials are typically required, with many travelers beginning their journeys from different points.

In contrast, quantum annealing begins with the traveler simultaneously occupying many coordinates thanks to the quantum phenomenon of superposition. The probability of being at any given coordinate smoothly evolves as annealing progresses, with the probability increasing around the coordinates of deep valleys. Quantum tunneling allows the traveller to pass through hillsrather than be forced to climb themreducing the chance of becoming trapped in valleys that are not the global minimum. Quantum entanglement further improves the outcome by allowing the traveler to discover correlations between the coordinates that lead to deep valleys.

The D-Wave system has a web API with client libraries available for C/C++, Python, and MATLAB. This allows users to access the computer easily as a cloud resource over a network.

To program the system, a user maps a problem into a search for the lowest point in a vast landscape, corresponding to the best possible outcome. The quantum processing unitconsiders all the possibilities simultaneously to determine the lowest energy required to form those relationships. The solutions are values that correspond to the optimal configurations of qubits found, or the lowest points in the energy landscape. These values are returned to the user program over the network.

Because a quantum computer is probabilistic rather than deterministic, the computer returns many very good answers in a short amount of timethousands of samples in one second. This provides not only the best solution found but also other very good alternatives from which to choose.

D-Wave systems are intended to be used to complement classical computers. There are many examples of problems where a quantum computer can complement an HPC (high-performance computing) system. While the quantum computer is well suited to discrete optimization, for example,the HPC system is better at large-scale numerical simulations.

Download this whitepaper to learn more about programming a D-Wave quantum computer.

D-Waves flagship product, the 2000qubit D-Wave 2000Q quantum computer, is the most advanced quantum computer in the world. It is based on a novel type of superconducting processor that uses quantum mechanics to massively accelerate computation. It is best suited to tackling complex optimization problems that exist across many domains such as:

Download the Technology Overview

View post:

Quantum Computing | D-Wave Systems

What are quantum computers and how do they work? WIRED …

Ray Orange

Google, IBM and a handful of startups are racing to create the next generation of supercomputers. Quantum computers, if they ever get started, will help us solve problems, like modelling complex chemical processes, that our existing computers can’t even scratch the surface of.

But the quantum future isn’t going to come easily, and there’s no knowing what it’ll look like when it does arrive. At the moment, companies and researchers are using a handful of different approaches to try and build the most powerful computers the world has ever seen. Here’s everything you need to know about the coming quantum revolution.

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

D-Wave

“The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called ‘entangled states’,” says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states at either of the two poles of the sphere a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something its calling quantum supremacy with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldnt hope to simulate, isnt exactly a widely accepted term within the quantum community. Those sceptical of Googles quantum project or at least the way it talks about quantum computing argue that supremacy is essentially an arbitrary goal set by Google to make it look like its making strides in quantum when really its just meeting self-imposed targets.

Whether its an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesnt necessarily mean theyve cracked supremacy and definitely doesnt mean that theyve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers dont consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, its likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, its possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers arent very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope theyll be able to use quantum simulations to design entirely new molecules for use in medicine. But the holy grail for quantum chemists is to be able to model the Haber-Bosch process a way of artificially producing ammonia that is still relatively inefficient. Researchers are hoping that if they can use quantum mechanics to work out whats going on inside that reaction, they could discover new ways to make the process much more efficient.

Continue reading here:

What are quantum computers and how do they work? WIRED …

What are quantum computers and how do they work? WIRED …

Ray Orange

Google, IBM and a handful of startups are racing to create the next generation of supercomputers. Quantum computers, if they ever get started, will help us solve problems, like modelling complex chemical processes, that our existing computers can’t even scratch the surface of.

But the quantum future isn’t going to come easily, and there’s no knowing what it’ll look like when it does arrive. At the moment, companies and researchers are using a handful of different approaches to try and build the most powerful computers the world has ever seen. Here’s everything you need to know about the coming quantum revolution.

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

D-Wave

“The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called ‘entangled states’,” says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states at either of the two poles of the sphere a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something its calling quantum supremacy with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldnt hope to simulate, isnt exactly a widely accepted term within the quantum community. Those sceptical of Googles quantum project or at least the way it talks about quantum computing argue that supremacy is essentially an arbitrary goal set by Google to make it look like its making strides in quantum when really its just meeting self-imposed targets.

Whether its an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesnt necessarily mean theyve cracked supremacy and definitely doesnt mean that theyve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers dont consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, its likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, its possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers arent very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope theyll be able to use quantum simulations to design entirely new molecules for use in medicine. But the holy grail for quantum chemists is to be able to model the Haber-Bosch process a way of artificially producing ammonia that is still relatively inefficient. Researchers are hoping that if they can use quantum mechanics to work out whats going on inside that reaction, they could discover new ways to make the process much more efficient.

Read more:

What are quantum computers and how do they work? WIRED …

Quantum Computing | D-Wave Systems

Quantum Computation

Rather than store information using bits represented by 0s or 1s as conventional digital computers do, quantum computers use quantum bits, or qubits, to encode information as 0s, 1s, or both at the same time. This superposition of statesalong with the other quantum mechanical phenomena of entanglement and tunnelingenables quantum computers to manipulate enormous combinations of states at once.

In nature, physical systems tend to evolve toward their lowest energy state: objects slide down hills, hot things cool down, and so on. This behavior also applies to quantum systems. To imagine this, think of a traveler looking for the best solution by finding the lowest valley in the energy landscape that represents the problem.

Classical algorithms seek the lowest valley by placing the traveler at some point in the landscape and allowing that traveler to move based on local variations. While it is generally most efficient to move downhill and avoid climbing hills that are too high, such classical algorithms are prone to leading the traveler into nearby valleys that may not be the global minimum. Numerous trials are typically required, with many travelers beginning their journeys from different points.

In contrast, quantum annealing begins with the traveler simultaneously occupying many coordinates thanks to the quantum phenomenon of superposition. The probability of being at any given coordinate smoothly evolves as annealing progresses, with the probability increasing around the coordinates of deep valleys. Quantum tunneling allows the traveller to pass through hillsrather than be forced to climb themreducing the chance of becoming trapped in valleys that are not the global minimum. Quantum entanglement further improves the outcome by allowing the traveler to discover correlations between the coordinates that lead to deep valleys.

The D-Wave system has a web API with client libraries available for C/C++, Python, and MATLAB. This allows users to access the computer easily as a cloud resource over a network.

To program the system, a user maps a problem into a search for the lowest point in a vast landscape, corresponding to the best possible outcome. The quantum processing unitconsiders all the possibilities simultaneously to determine the lowest energy required to form those relationships. The solutions are values that correspond to the optimal configurations of qubits found, or the lowest points in the energy landscape. These values are returned to the user program over the network.

Because a quantum computer is probabilistic rather than deterministic, the computer returns many very good answers in a short amount of timethousands of samples in one second. This provides not only the best solution found but also other very good alternatives from which to choose.

D-Wave systems are intended to be used to complement classical computers. There are many examples of problems where a quantum computer can complement an HPC (high-performance computing) system. While the quantum computer is well suited to discrete optimization, for example,the HPC system is better at large-scale numerical simulations.

Download this whitepaper to learn more about programming a D-Wave quantum computer.

D-Waves flagship product, the 2000qubit D-Wave 2000Q quantum computer, is the most advanced quantum computer in the world. It is based on a novel type of superconducting processor that uses quantum mechanics to massively accelerate computation. It is best suited to tackling complex optimization problems that exist across many domains such as:

Download the Technology Overview

Go here to see the original:

Quantum Computing | D-Wave Systems

Quantum Computing Explained – WIRED UK

Ray Orange

Google, IBM and a handful of startups are racing to create the next generation of supercomputers. Quantum computers, if they ever get started, will help us solve problems, like modelling complex chemical processes, that our existing computers can’t even scratch the surface of.

But the quantum future isn’t going to come easily, and there’s no knowing what it’ll look like when it does arrive. At the moment, companies and researchers are using a handful of different approaches to try and build the most powerful computers the world has ever seen. Here’s everything you need to know about the coming quantum revolution.

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

D-Wave

“The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called ‘entangled states’,” says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states at either of the two poles of the sphere a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something its calling quantum supremacy with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldnt hope to simulate, isnt exactly a widely accepted term within the quantum community. Those sceptical of Googles quantum project or at least the way it talks about quantum computing argue that supremacy is essentially an arbitrary goal set by Google to make it look like its making strides in quantum when really its just meeting self-imposed targets.

Whether its an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesnt necessarily mean theyve cracked supremacy and definitely doesnt mean that theyve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers dont consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, its likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, its possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers arent very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope theyll be able to use quantum simulations to design entirely new molecules for use in medicine. But the holy grail for quantum chemists is to be able to model the Haber-Bosch process a way of artificially producing ammonia that is still relatively inefficient. Researchers are hoping that if they can use quantum mechanics to work out whats going on inside that reaction, they could discover new ways to make the process much more efficient.

Continue reading here:

Quantum Computing Explained – WIRED UK

Quantum Computing | D-Wave Systems

Quantum Computation

Rather than store information using bits represented by 0s or 1s as conventional digital computers do, quantum computers use quantum bits, or qubits, to encode information as 0s, 1s, or both at the same time. This superposition of statesalong with the other quantum mechanical phenomena of entanglement and tunnelingenables quantum computers to manipulate enormous combinations of states at once.

In nature, physical systems tend to evolve toward their lowest energy state: objects slide down hills, hot things cool down, and so on. This behavior also applies to quantum systems. To imagine this, think of a traveler looking for the best solution by finding the lowest valley in the energy landscape that represents the problem.

Classical algorithms seek the lowest valley by placing the traveler at some point in the landscape and allowing that traveler to move based on local variations. While it is generally most efficient to move downhill and avoid climbing hills that are too high, such classical algorithms are prone to leading the traveler into nearby valleys that may not be the global minimum. Numerous trials are typically required, with many travelers beginning their journeys from different points.

In contrast, quantum annealing begins with the traveler simultaneously occupying many coordinates thanks to the quantum phenomenon of superposition. The probability of being at any given coordinate smoothly evolves as annealing progresses, with the probability increasing around the coordinates of deep valleys. Quantum tunneling allows the traveller to pass through hillsrather than be forced to climb themreducing the chance of becoming trapped in valleys that are not the global minimum. Quantum entanglement further improves the outcome by allowing the traveler to discover correlations between the coordinates that lead to deep valleys.

The D-Wave system has a web API with client libraries available for C/C++, Python, and MATLAB. This allows users to access the computer easily as a cloud resource over a network.

To program the system, a user maps a problem into a search for the lowest point in a vast landscape, corresponding to the best possible outcome. The quantum processing unitconsiders all the possibilities simultaneously to determine the lowest energy required to form those relationships. The solutions are values that correspond to the optimal configurations of qubits found, or the lowest points in the energy landscape. These values are returned to the user program over the network.

Because a quantum computer is probabilistic rather than deterministic, the computer returns many very good answers in a short amount of timethousands of samples in one second. This provides not only the best solution found but also other very good alternatives from which to choose.

D-Wave systems are intended to be used to complement classical computers. There are many examples of problems where a quantum computer can complement an HPC (high-performance computing) system. While the quantum computer is well suited to discrete optimization, for example,the HPC system is better at large-scale numerical simulations.

Download this whitepaper to learn more about programming a D-Wave quantum computer.

D-Waves flagship product, the 2000qubit D-Wave 2000Q quantum computer, is the most advanced quantum computer in the world. It is based on a novel type of superconducting processor that uses quantum mechanics to massively accelerate computation. It is best suited to tackling complex optimization problems that exist across many domains such as:

Download the Technology Overview

Read more:

Quantum Computing | D-Wave Systems

Quantum Computing Explained – WIRED UK

Ray Orange

Google, IBM and a handful of startups are racing to create the next generation of supercomputers. Quantum computers, if they ever get started, will help us solve problems, like modelling complex chemical processes, that our existing computers can’t even scratch the surface of.

But the quantum future isn’t going to come easily, and there’s no knowing what it’ll look like when it does arrive. At the moment, companies and researchers are using a handful of different approaches to try and build the most powerful computers the world has ever seen. Here’s everything you need to know about the coming quantum revolution.

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

D-Wave

“The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called ‘entangled states’,” says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states at either of the two poles of the sphere a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something its calling quantum supremacy with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldnt hope to simulate, isnt exactly a widely accepted term within the quantum community. Those sceptical of Googles quantum project or at least the way it talks about quantum computing argue that supremacy is essentially an arbitrary goal set by Google to make it look like its making strides in quantum when really its just meeting self-imposed targets.

Whether its an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesnt necessarily mean theyve cracked supremacy and definitely doesnt mean that theyve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers dont consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, its likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, its possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers arent very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope theyll be able to use quantum simulations to design entirely new molecules for use in medicine. But the holy grail for quantum chemists is to be able to model the Haber-Bosch process a way of artificially producing ammonia that is still relatively inefficient. Researchers are hoping that if they can use quantum mechanics to work out whats going on inside that reaction, they could discover new ways to make the process much more efficient.

Read more:

Quantum Computing Explained – WIRED UK

Quantum computing: A simple introduction – Explain that Stuff

by Chris Woodford. Last updated: March 9, 2018.

How can you get more and more out of less and less? The smaller computers get, the more powerful they seem to become: there’s more number-crunching ability in a 21st-century cellphone than you’d have found in a room-sized, military computer 50 years ago. Yet, despitesuch amazing advances, there are still plenty of complex problemsthat are beyond the reach of even the world’s most powerfulcomputersand there’s no guarantee we’ll ever be able to tacklethem. One problem is that the basic switching and memory units ofcomputers, known as transistors, are now approaching the point wherethey’ll soon be as small as individual atoms. If we want computersthat are smaller and more powerful than today’s, we’ll soon need todo our computing in a radically different way. Entering the realm ofatoms opens up powerful new possibilities in the shape of quantumcomputing, with processors that could work millions of timesfaster than the ones we use today. Sounds amazing, but the trouble isthat quantum computing is hugely more complex than traditionalcomputing and operates in the Alice in Wonderland world of quantumphysics, where the “classical,” sensible, everyday laws of physics no longer apply. What isquantum computing and how does it work? Let’s take a closer look!

Photo: Quantum computing means storing and processing information using individual atoms, ions, electrons, or photons. On the plus side, this opens up the possibility of faster computers, but the drawback is the greater complexity of designing computers that can operate in the weird world of quantum physics.

You probably think of a computer as a neat little gadget that sits on your lap and lets you send emails, shop online, chat to your friends, or play gamesbut it’s much moreand much lessthan that. It’s more, because it’s a completely general-purposemachine: you can make it do virtually anything you like. It’sless, because inside it’s little more than an extremely basiccalculator, following a prearranged set of instructions called aprogram. Like the Wizard of Oz, the amazing things you see in front of youconceal some pretty mundane stuff under the covers.

Photo: This is what one transistor from a typical radio circuit board looks like. In computers, the transistors are much smaller than this and millions of them are packaged together onto microchips.

Conventional computers have two tricks that they do really well: they can storenumbers in memory and they can process stored numbers with simple mathematical operations (like add and subtract). They can do more complex things by stringing together the simple operations into a series called an algorithm (multiplying can bedone as a series of additions, for example). Both of a computer’s keytricksstorage and processingare accomplished using switchescalled transistors, which are like microscopic versions of theswitches you have on your wall for turning on and off the lights. Atransistor can either be on or off, just as a light can either be litor unlit. If it’s on, we can use a transistor to store a number one(1); if it’s off, it stores a number zero (0). Long strings of onesand zeros can be used to store any number, letter, or symbol using acode based on binary (so computers store an upper-case letter A as1000001 and a lower-case one as 01100001). Each of the zeros or ones is called a binary digit (or bit) and, with a string of eight bits, you can store 255 differentcharacters (such as A-Z, a-z, 0-9, and most common symbols).Computers calculate by using circuits called logic gates,which are made from a number of transistors connected together. Logicgates compare patterns of bits, stored in temporary memories calledregisters, and then turn them into new patterns of bitsandthat’s the computer equivalent of what our human brains would calladdition, subtraction, or multiplication. In physical terms, thealgorithm that performs a particular calculation takes the form of anelectronic circuit made from a number of logic gates, with the output from one gate feeding in as the input to the next.

The trouble with conventional computers is that they depend onconventional transistors. This might not sound like a problem if yougo by the amazing progress made in electronics over the last fewdecades. When the transistor was invented, back in 1947, the switchit replaced (which was called the vacuum tube) was about asbig as one of your thumbs. Now, a state-of-the-art microprocessor(single-chip computer) packs hundreds of millions (and up to twobillion) transistors onto a chip of silicon the size of yourfingernail! Chips like these, which are called integrated circuits, are an incredible feat of miniaturization. Back in the1960s, Intel co-founder Gordon Moore realized that the power ofcomputers doubles roughly 18 monthsand it’s been doing so eversince. This apparently unshakeable trend is known as Moore’s Law.

Photo: This memory chip from a typical USB stick contains an integrated circuit that can store 512 megabytes of data. That’s roughly 500 million characters (536,870,912 to be exact), each of which needs eight binary digitsso we’re talking about 4 billion (4,000 million) transistors in all (4,294,967,296 if you’re being picky) packed into an area the size of a postage stamp!

It sounds amazing, and it is, but it misses the point. The moreinformation you need to store, the more binary ones and zerosandtransistorsyou need to do it. Since most conventional computers canonly do one thing at a time, the more complex the problem you wantthem to solve, the more steps they’ll need to take and the longerthey’ll need to do it. Some computing problems are so complex thatthey need more computing power and time than any modern machine couldreasonably supply; computer scientists call those intractableproblems.

As Moore’s Law advances, so the number of intractable problemsdiminishes: computers get more powerful and we can do more with them.The trouble is, transistors are just about as small as we can makethem: we’re getting to the point where the laws of physics seem likelyto put a stop to Moore’s Law. Unfortunately, there are still hugelydifficult computing problems we can’t tackle because even the mostpowerful computers find them intractable. That’s one of the reasonswhy people are now getting interested in quantum computing.

Things on a very small scale behave like nothing you have any direct experience about… or like anything that you have ever seen.

Richard Feynman

Quantum theory is the branch of physics that deals with the world ofatoms and the smaller (subatomic) particles inside them. You mightthink atoms behave the same way as everything else in the world, intheir own tiny little waybut that’s not true: on the atomic scale, the rules change and the “classical” laws of physics we take for granted in our everyday world no longer automatically apply. As Richard P. Feynman,one of the greatest physicists of the 20th century, once put it: “Things on a very small scale behave like nothing you have any direct experience about… or like anything that you have ever seen.” (Six Easy Pieces, p116.)

If you’ve studied light, you may already know a bit about quantumtheory. You might know that a beam of light sometimes behaves asthough it’s made up of particles (like a steady stream ofcannonballs), and sometimes as though it’s waves of energy ripplingthrough space (a bit like waves on the sea). That’s called wave-particle dualityand it’s one of the ideas that comes to us from quantum theory. It’s hard to grasp thatsomething can be two things at oncea particle and awavebecause it’s totally alien to our everyday experience: a car isnot simultaneously a bicycle and a bus. In quantum theory, however,that’s just the kind of crazy thing that can happen. The most striking example of this is the baffling riddle known as Schrdinger’s cat. Briefly, in the weird world ofquantum theory, we can imagine a situation where something like a catcould be alive and dead at the same time!

What does all this have to do with computers? Suppose we keep on pushingMoore’s Lawkeep on making transistors smaller until they get to thepoint where they obey not the ordinary laws of physics (likeold-style transistors) but the more bizarre laws of quantummechanics. The question is whether computers designed this way can dothings our conventional computers can’t. If we can predictmathematically that they might be able to, can we actually make themwork like that in practice?

People have been asking those questions for several decades.Among the first were IBM research physicists Rolf Landauer and Charles H. Bennett. Landauer opened the door for quantumcomputing in the 1960s when he proposed that information is a physical entitythat could be manipulated according to the laws of physics.One important consequence of this is that computers waste energy manipulating the bits inside them(which is partly why computers use so much energy and get so hot, even though they appear to be doingnot very much at all). In the 1970s, building on Landauer’s work, Bennett showed how a computer could circumventthis problem by working in a “reversible” way, implying that a quantum computer couldcarry out massively complex computations without using massive amounts of energy.In 1981, physicist Paul Benioff from Argonne National Laboratory tried to envisage a basic machine that would work in a similar way to an ordinary computer but according to the principlesof quantum physics. The following year, Richard Feynman sketched out roughly how a machine using quantum principles could carry out basiccomputations. A few years later, Oxford University’s David Deutsch(one of the leading lights in quantum computing) outlined thetheoretical basis of a quantum computer in more detail. How did thesegreat scientists imagine that quantum computers might work?

The key features of an ordinary computerbits, registers, logic gates,algorithms, and so onhave analogous features in a quantum computer.Instead of bits, a quantum computer has quantum bits or qubits,which work in a particularly intriguing way. Where a bit can storeeither a zero or a 1, a qubit can store a zero, a one, bothzero and one, or an infinite number of values in betweenandbe in multiple states (store multiple values) at the same time!If that sounds confusing, think back to light being a particle anda wave at the same time, Schrdinger’s cat being alive and dead, or acar being a bicycle and a bus. A gentler way to think of the numbersqubits store is through the physics concept of superposition(where two waves add to make a third one that contains both of theoriginals). If you blow on something like a flute, the pipe fills upwith a standing wave: a wave made up of a fundamental frequency (thebasic note you’re playing) and lots of overtones or harmonics(higher-frequency multiples of the fundamental). The wave inside thepipe contains all these waves simultaneously: they’re added togetherto make a combined wave that includes them all. Qubits usesuperposition to represent multiple states (multiple numeric values)simultaneously in a similar way.

Just as a quantum computer can store multiple numbers at once, so it canprocess them simultaneously. Instead of working in serial (doing aseries of things one at a time in a sequence), it can work inparallel (doing multiple things at the same time). Only when youtry to find out what state it’s actually in at any given moment(by measuring it, in other words) does it “collapse” into one of its possible statesandthat gives you the answer to your problem. Estimates suggesta quantum computer’s ability to work in parallel would make it millions of times faster thanany conventional computer… if only we could build it! So howwould we do that?

In reality, qubits would have to be stored by atoms, ions (atoms withtoo many or too few electrons), or even smaller things such as electronsand photons (energy packets), so a quantum computer would be almost like a table-topversion of the kind of particle physics experiments they do atFermilab or CERN. Now you wouldn’t be racing particles round giantloops and smashing them together, but you would need mechanisms forcontaining atoms, ions, or subatomic particles, for putting them into certainstates (so you can store information), knocking them into other states (so you canmake them process information), and figuring out what their states are after particularoperations have been performed.

Photo: A single atom can be trapped in an optical cavitythe space between mirrorsand controlled by precise pulses from laser beams.

In practice, there are lots of possible ways of containing atoms and changing their states usinglaser beams, electromagneticfields, radio waves, and an assortment of other techniques.One method is to make qubits usingquantum dots, which are nanoscopically tiny particles of semiconductors inside which individual charge carriers, electrons and holes (missing electrons), can be controlled. Another methodmakes qubits from what are called ion traps: you add or take awayelectrons from an atom to make an ion, hold it steady in a kind of laser spotlight(so it’s locked in place like a nanoscopic rabbit dancing in a very bright headlight),and then flip it into different states with laser pulses. In another technique,the qubits are photons inside optical cavities (spaces betweenextremely tiny mirrors). Don’t worry if you don’t understand; not many people do. Since the entirefield of quantum computing is still largely abstract and theoretical, the only thing we really need to knowis that qubits are stored by atoms or other quantum-scale particles that canexist in different states and be switched between them.

Although people often assume that quantum computers must automatically bebetter than conventional ones, that’s by no means certain. So far,just about the only thing we know for certain that a quantum computer could do better than anormal one is factorisation: finding two unknown prime numbers that,when multiplied together, give a third, known number. In 1994,while working at Bell Laboratories, mathematician Peter Shor demonstrated an algorithm that a quantum computercould follow to find the “prime factors” of a large number, whichwould speed up the problem enormously. Shor’s algorithm reallyexcited interest in quantum computing because virtually every moderncomputer (and every secure, online shopping and banking website) usespublic-key encryption technology based on the virtual impossibility of finding prime factors quickly (it is, in other words, essentiallyan “intractable” computer problem). If quantum computers couldindeed factor large numbers quickly, today’s online security could berendered obsolete at a stroke. But what goes around comes around,and some researchers believe quantum technology will lead tomuch stronger forms of encryption.(In 2017, Chinese researchers demonstrated for the first timehow quantum encryption could be used to make a very secure video callfrom Beijing to Vienna.)

Does that mean quantum computers are better than conventional ones? Notexactly. Apart from Shor’s algorithm, and a search method called Grover’s algorithm, hardly any other algorithms have been discovered that wouldbe better performed by quantum methods. Given enough time andcomputing power, conventional computers should still be able to solveany problem that quantum computers could solve, eventually. Inother words, it remains to be proven that quantum computers aregenerally superior to conventional ones, especially given the difficulties ofactually building them. Who knows how conventional computers might advancein the next 50 years, potentially making the idea of quantum computers irrelevantand even absurd.

Photo: Quantum dots are probably best known as colorful nanoscale crystals, but they can also be used as qubits in quantum computers). Photo courtesy of Argonne National Laboratory.

Three decades after they were first proposed, quantum computers remainlargely theoretical. Even so, there’s been some encouraging progresstoward realizing a quantum machine. There were two impressivebreakthroughs in 2000. First, Isaac Chuang (now an MIT professor, but then working at IBM’sAlmaden Research Center) used five fluorine atoms to make a crude,five-qubit quantum computer. The same year, researchers at LosAlamos National Laboratory figured out how to make a seven-qubitmachine using a drop of liquid. Five years later, researchers at theUniversity of Innsbruck added an extra qubit and produced the firstquantum computer that could manipulate a qubyte (eight qubits).

These were tentative but important first steps.Over the next few years, researchers announced more ambitious experiments, addingprogressively greater numbers of qubits. By 2011, a pioneering Canadiancompany called D-Wave Systems announced in Nature that it had produced a 128-qubitmachine; the announcement proved highly controversialand there was a lot of debate over whether the company’s machines had really demonstrated quantum behavior.Three years later, Google announced that it was hiring a team of academics (including University of Californiaat Santa Barbara physicist John Martinis) to develop its own quantum computers based on D-Wave’s approach.In March 2015, the Google team announced they were “a step closer to quantum computation,” having developeda new way for qubits to detect and protect against errors.In 2016, MIT’s Isaac Chuang and scientists from the University of Innsbruckunveiled a five-qubit, ion-trap quantum computer that could calculate the factors of 15; one day, a scaled-up version of this machine mightevolve into the long-promised, fully fledged encryption buster.

There’s no doubt that these are hugely important advances.and the signs are growing steadily more encouraging that quantumtechnology will eventually deliver a computing revolution.In December 2017, Microsoft unveiled a completequantum development kit, including a new computer language, Q#, developed specifically forquantum applications. In early 2018,D-wave announced plans to start rolling out quantum power to acloud computing platform.A few weeks later, Google announced Bristlecone, a quantum processorbased on a 72-qubit array, that might, one day, form the cornerstone of a quantum computer that could tackle real-world problems.All very exciting! Even so, it’s early days for the whole field, and mostresearchers agree that we’re unlikely to see practical quantumcomputers appearing for some yearsand more likely several decades.

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Quantum computing: A simple introduction – Explain that Stuff

Quantum computing: A simple introduction – Explain that Stuff

by Chris Woodford. Last updated: March 9, 2018.

How can you get more and more out of less and less? The smaller computers get, the more powerful they seem to become: there’s more number-crunching ability in a 21st-century cellphone than you’d have found in a room-sized, military computer 50 years ago. Yet, despitesuch amazing advances, there are still plenty of complex problemsthat are beyond the reach of even the world’s most powerfulcomputersand there’s no guarantee we’ll ever be able to tacklethem. One problem is that the basic switching and memory units ofcomputers, known as transistors, are now approaching the point wherethey’ll soon be as small as individual atoms. If we want computersthat are smaller and more powerful than today’s, we’ll soon need todo our computing in a radically different way. Entering the realm ofatoms opens up powerful new possibilities in the shape of quantumcomputing, with processors that could work millions of timesfaster than the ones we use today. Sounds amazing, but the trouble isthat quantum computing is hugely more complex than traditionalcomputing and operates in the Alice in Wonderland world of quantumphysics, where the “classical,” sensible, everyday laws of physics no longer apply. What isquantum computing and how does it work? Let’s take a closer look!

Photo: Quantum computing means storing and processing information using individual atoms, ions, electrons, or photons. On the plus side, this opens up the possibility of faster computers, but the drawback is the greater complexity of designing computers that can operate in the weird world of quantum physics.

You probably think of a computer as a neat little gadget that sits on your lap and lets you send emails, shop online, chat to your friends, or play gamesbut it’s much moreand much lessthan that. It’s more, because it’s a completely general-purposemachine: you can make it do virtually anything you like. It’sless, because inside it’s little more than an extremely basiccalculator, following a prearranged set of instructions called aprogram. Like the Wizard of Oz, the amazing things you see in front of youconceal some pretty mundane stuff under the covers.

Photo: This is what one transistor from a typical radio circuit board looks like. In computers, the transistors are much smaller than this and millions of them are packaged together onto microchips.

Conventional computers have two tricks that they do really well: they can storenumbers in memory and they can process stored numbers with simple mathematical operations (like add and subtract). They can do more complex things by stringing together the simple operations into a series called an algorithm (multiplying can bedone as a series of additions, for example). Both of a computer’s keytricksstorage and processingare accomplished using switchescalled transistors, which are like microscopic versions of theswitches you have on your wall for turning on and off the lights. Atransistor can either be on or off, just as a light can either be litor unlit. If it’s on, we can use a transistor to store a number one(1); if it’s off, it stores a number zero (0). Long strings of onesand zeros can be used to store any number, letter, or symbol using acode based on binary (so computers store an upper-case letter A as1000001 and a lower-case one as 01100001). Each of the zeros or ones is called a binary digit (or bit) and, with a string of eight bits, you can store 255 differentcharacters (such as A-Z, a-z, 0-9, and most common symbols).Computers calculate by using circuits called logic gates,which are made from a number of transistors connected together. Logicgates compare patterns of bits, stored in temporary memories calledregisters, and then turn them into new patterns of bitsandthat’s the computer equivalent of what our human brains would calladdition, subtraction, or multiplication. In physical terms, thealgorithm that performs a particular calculation takes the form of anelectronic circuit made from a number of logic gates, with the output from one gate feeding in as the input to the next.

The trouble with conventional computers is that they depend onconventional transistors. This might not sound like a problem if yougo by the amazing progress made in electronics over the last fewdecades. When the transistor was invented, back in 1947, the switchit replaced (which was called the vacuum tube) was about asbig as one of your thumbs. Now, a state-of-the-art microprocessor(single-chip computer) packs hundreds of millions (and up to twobillion) transistors onto a chip of silicon the size of yourfingernail! Chips like these, which are called integrated circuits, are an incredible feat of miniaturization. Back in the1960s, Intel co-founder Gordon Moore realized that the power ofcomputers doubles roughly 18 monthsand it’s been doing so eversince. This apparently unshakeable trend is known as Moore’s Law.

Photo: This memory chip from a typical USB stick contains an integrated circuit that can store 512 megabytes of data. That’s roughly 500 million characters (536,870,912 to be exact), each of which needs eight binary digitsso we’re talking about 4 billion (4,000 million) transistors in all (4,294,967,296 if you’re being picky) packed into an area the size of a postage stamp!

It sounds amazing, and it is, but it misses the point. The moreinformation you need to store, the more binary ones and zerosandtransistorsyou need to do it. Since most conventional computers canonly do one thing at a time, the more complex the problem you wantthem to solve, the more steps they’ll need to take and the longerthey’ll need to do it. Some computing problems are so complex thatthey need more computing power and time than any modern machine couldreasonably supply; computer scientists call those intractableproblems.

As Moore’s Law advances, so the number of intractable problemsdiminishes: computers get more powerful and we can do more with them.The trouble is, transistors are just about as small as we can makethem: we’re getting to the point where the laws of physics seem likelyto put a stop to Moore’s Law. Unfortunately, there are still hugelydifficult computing problems we can’t tackle because even the mostpowerful computers find them intractable. That’s one of the reasonswhy people are now getting interested in quantum computing.

Things on a very small scale behave like nothing you have any direct experience about… or like anything that you have ever seen.

Richard Feynman

Quantum theory is the branch of physics that deals with the world ofatoms and the smaller (subatomic) particles inside them. You mightthink atoms behave the same way as everything else in the world, intheir own tiny little waybut that’s not true: on the atomic scale, the rules change and the “classical” laws of physics we take for granted in our everyday world no longer automatically apply. As Richard P. Feynman,one of the greatest physicists of the 20th century, once put it: “Things on a very small scale behave like nothing you have any direct experience about… or like anything that you have ever seen.” (Six Easy Pieces, p116.)

If you’ve studied light, you may already know a bit about quantumtheory. You might know that a beam of light sometimes behaves asthough it’s made up of particles (like a steady stream ofcannonballs), and sometimes as though it’s waves of energy ripplingthrough space (a bit like waves on the sea). That’s called wave-particle dualityand it’s one of the ideas that comes to us from quantum theory. It’s hard to grasp thatsomething can be two things at oncea particle and awavebecause it’s totally alien to our everyday experience: a car isnot simultaneously a bicycle and a bus. In quantum theory, however,that’s just the kind of crazy thing that can happen. The most striking example of this is the baffling riddle known as Schrdinger’s cat. Briefly, in the weird world ofquantum theory, we can imagine a situation where something like a catcould be alive and dead at the same time!

What does all this have to do with computers? Suppose we keep on pushingMoore’s Lawkeep on making transistors smaller until they get to thepoint where they obey not the ordinary laws of physics (likeold-style transistors) but the more bizarre laws of quantummechanics. The question is whether computers designed this way can dothings our conventional computers can’t. If we can predictmathematically that they might be able to, can we actually make themwork like that in practice?

People have been asking those questions for several decades.Among the first were IBM research physicists Rolf Landauer and Charles H. Bennett. Landauer opened the door for quantumcomputing in the 1960s when he proposed that information is a physical entitythat could be manipulated according to the laws of physics.One important consequence of this is that computers waste energy manipulating the bits inside them(which is partly why computers use so much energy and get so hot, even though they appear to be doingnot very much at all). In the 1970s, building on Landauer’s work, Bennett showed how a computer could circumventthis problem by working in a “reversible” way, implying that a quantum computer couldcarry out massively complex computations without using massive amounts of energy.In 1981, physicist Paul Benioff from Argonne National Laboratory tried to envisage a basic machine that would work in a similar way to an ordinary computer but according to the principlesof quantum physics. The following year, Richard Feynman sketched out roughly how a machine using quantum principles could carry out basiccomputations. A few years later, Oxford University’s David Deutsch(one of the leading lights in quantum computing) outlined thetheoretical basis of a quantum computer in more detail. How did thesegreat scientists imagine that quantum computers might work?

The key features of an ordinary computerbits, registers, logic gates,algorithms, and so onhave analogous features in a quantum computer.Instead of bits, a quantum computer has quantum bits or qubits,which work in a particularly intriguing way. Where a bit can storeeither a zero or a 1, a qubit can store a zero, a one, bothzero and one, or an infinite number of values in betweenandbe in multiple states (store multiple values) at the same time!If that sounds confusing, think back to light being a particle anda wave at the same time, Schrdinger’s cat being alive and dead, or acar being a bicycle and a bus. A gentler way to think of the numbersqubits store is through the physics concept of superposition(where two waves add to make a third one that contains both of theoriginals). If you blow on something like a flute, the pipe fills upwith a standing wave: a wave made up of a fundamental frequency (thebasic note you’re playing) and lots of overtones or harmonics(higher-frequency multiples of the fundamental). The wave inside thepipe contains all these waves simultaneously: they’re added togetherto make a combined wave that includes them all. Qubits usesuperposition to represent multiple states (multiple numeric values)simultaneously in a similar way.

Just as a quantum computer can store multiple numbers at once, so it canprocess them simultaneously. Instead of working in serial (doing aseries of things one at a time in a sequence), it can work inparallel (doing multiple things at the same time). Only when youtry to find out what state it’s actually in at any given moment(by measuring it, in other words) does it “collapse” into one of its possible statesandthat gives you the answer to your problem. Estimates suggesta quantum computer’s ability to work in parallel would make it millions of times faster thanany conventional computer… if only we could build it! So howwould we do that?

In reality, qubits would have to be stored by atoms, ions (atoms withtoo many or too few electrons), or even smaller things such as electronsand photons (energy packets), so a quantum computer would be almost like a table-topversion of the kind of particle physics experiments they do atFermilab or CERN. Now you wouldn’t be racing particles round giantloops and smashing them together, but you would need mechanisms forcontaining atoms, ions, or subatomic particles, for putting them into certainstates (so you can store information), knocking them into other states (so you canmake them process information), and figuring out what their states are after particularoperations have been performed.

Photo: A single atom can be trapped in an optical cavitythe space between mirrorsand controlled by precise pulses from laser beams.

In practice, there are lots of possible ways of containing atoms and changing their states usinglaser beams, electromagneticfields, radio waves, and an assortment of other techniques.One method is to make qubits usingquantum dots, which are nanoscopically tiny particles of semiconductors inside which individual charge carriers, electrons and holes (missing electrons), can be controlled. Another methodmakes qubits from what are called ion traps: you add or take awayelectrons from an atom to make an ion, hold it steady in a kind of laser spotlight(so it’s locked in place like a nanoscopic rabbit dancing in a very bright headlight),and then flip it into different states with laser pulses. In another technique,the qubits are photons inside optical cavities (spaces betweenextremely tiny mirrors). Don’t worry if you don’t understand; not many people do. Since the entirefield of quantum computing is still largely abstract and theoretical, the only thing we really need to knowis that qubits are stored by atoms or other quantum-scale particles that canexist in different states and be switched between them.

Although people often assume that quantum computers must automatically bebetter than conventional ones, that’s by no means certain. So far,just about the only thing we know for certain that a quantum computer could do better than anormal one is factorisation: finding two unknown prime numbers that,when multiplied together, give a third, known number. In 1994,while working at Bell Laboratories, mathematician Peter Shor demonstrated an algorithm that a quantum computercould follow to find the “prime factors” of a large number, whichwould speed up the problem enormously. Shor’s algorithm reallyexcited interest in quantum computing because virtually every moderncomputer (and every secure, online shopping and banking website) usespublic-key encryption technology based on the virtual impossibility of finding prime factors quickly (it is, in other words, essentiallyan “intractable” computer problem). If quantum computers couldindeed factor large numbers quickly, today’s online security could berendered obsolete at a stroke. But what goes around comes around,and some researchers believe quantum technology will lead tomuch stronger forms of encryption.(In 2017, Chinese researchers demonstrated for the first timehow quantum encryption could be used to make a very secure video callfrom Beijing to Vienna.)

Does that mean quantum computers are better than conventional ones? Notexactly. Apart from Shor’s algorithm, and a search method called Grover’s algorithm, hardly any other algorithms have been discovered that wouldbe better performed by quantum methods. Given enough time andcomputing power, conventional computers should still be able to solveany problem that quantum computers could solve, eventually. Inother words, it remains to be proven that quantum computers aregenerally superior to conventional ones, especially given the difficulties ofactually building them. Who knows how conventional computers might advancein the next 50 years, potentially making the idea of quantum computers irrelevantand even absurd.

Photo: Quantum dots are probably best known as colorful nanoscale crystals, but they can also be used as qubits in quantum computers). Photo courtesy of Argonne National Laboratory.

Three decades after they were first proposed, quantum computers remainlargely theoretical. Even so, there’s been some encouraging progresstoward realizing a quantum machine. There were two impressivebreakthroughs in 2000. First, Isaac Chuang (now an MIT professor, but then working at IBM’sAlmaden Research Center) used five fluorine atoms to make a crude,five-qubit quantum computer. The same year, researchers at LosAlamos National Laboratory figured out how to make a seven-qubitmachine using a drop of liquid. Five years later, researchers at theUniversity of Innsbruck added an extra qubit and produced the firstquantum computer that could manipulate a qubyte (eight qubits).

These were tentative but important first steps.Over the next few years, researchers announced more ambitious experiments, addingprogressively greater numbers of qubits. By 2011, a pioneering Canadiancompany called D-Wave Systems announced in Nature that it had produced a 128-qubitmachine; the announcement proved highly controversialand there was a lot of debate over whether the company’s machines had really demonstrated quantum behavior.Three years later, Google announced that it was hiring a team of academics (including University of Californiaat Santa Barbara physicist John Martinis) to develop its own quantum computers based on D-Wave’s approach.In March 2015, the Google team announced they were “a step closer to quantum computation,” having developeda new way for qubits to detect and protect against errors.In 2016, MIT’s Isaac Chuang and scientists from the University of Innsbruckunveiled a five-qubit, ion-trap quantum computer that could calculate the factors of 15; one day, a scaled-up version of this machine mightevolve into the long-promised, fully fledged encryption buster.

There’s no doubt that these are hugely important advances.and the signs are growing steadily more encouraging that quantumtechnology will eventually deliver a computing revolution.In December 2017, Microsoft unveiled a completequantum development kit, including a new computer language, Q#, developed specifically forquantum applications. In early 2018,D-wave announced plans to start rolling out quantum power to acloud computing platform.A few weeks later, Google announced Bristlecone, a quantum processorbased on a 72-qubit array, that might, one day, form the cornerstone of a quantum computer that could tackle real-world problems.All very exciting! Even so, it’s early days for the whole field, and mostresearchers agree that we’re unlikely to see practical quantumcomputers appearing for some yearsand more likely several decades.

See the original post:

Quantum computing: A simple introduction – Explain that Stuff

Quantum Computing Explained – WIRED UK

Ray Orange

Google, IBM and a handful of startups are racing to create the next generation of supercomputers. Quantum computers, if they ever get started, will help us solve problems, like modelling complex chemical processes, that our existing computers can’t even scratch the surface of.

But the quantum future isn’t going to come easily, and there’s no knowing what it’ll look like when it does arrive. At the moment, companies and researchers are using a handful of different approaches to try and build the most powerful computers the world has ever seen. Here’s everything you need to know about the coming quantum revolution.

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

D-Wave

“The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called ‘entangled states’,” says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states at either of the two poles of the sphere a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something its calling quantum supremacy with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldnt hope to simulate, isnt exactly a widely accepted term within the quantum community. Those sceptical of Googles quantum project or at least the way it talks about quantum computing argue that supremacy is essentially an arbitrary goal set by Google to make it look like its making strides in quantum when really its just meeting self-imposed targets.

Whether its an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesnt necessarily mean theyve cracked supremacy and definitely doesnt mean that theyve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers dont consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, its likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, its possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers arent very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope theyll be able to use quantum simulations to design entirely new molecules for use in medicine. But the holy grail for quantum chemists is to be able to model the Haber-Bosch process a way of artificially producing ammonia that is still relatively inefficient. Researchers are hoping that if they can use quantum mechanics to work out whats going on inside that reaction, they could discover new ways to make the process much more efficient.

More here:

Quantum Computing Explained – WIRED UK

Quantum Computing Explained – WIRED UK

Ray Orange

Google, IBM and a handful of startups are racing to create the next generation of supercomputers. Quantum computers, if they ever get started, will help us solve problems, like modelling complex chemical processes, that our existing computers can’t even scratch the surface of.

But the quantum future isn’t going to come easily, and there’s no knowing what it’ll look like when it does arrive. At the moment, companies and researchers are using a handful of different approaches to try and build the most powerful computers the world has ever seen. Here’s everything you need to know about the coming quantum revolution.

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

D-Wave

“The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called ‘entangled states’,” says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states at either of the two poles of the sphere a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something its calling quantum supremacy with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldnt hope to simulate, isnt exactly a widely accepted term within the quantum community. Those sceptical of Googles quantum project or at least the way it talks about quantum computing argue that supremacy is essentially an arbitrary goal set by Google to make it look like its making strides in quantum when really its just meeting self-imposed targets.

Whether its an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesnt necessarily mean theyve cracked supremacy and definitely doesnt mean that theyve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers dont consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, its likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, its possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers arent very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope theyll be able to use quantum simulations to design entirely new molecules for use in medicine. But the holy grail for quantum chemists is to be able to model the Haber-Bosch process a way of artificially producing ammonia that is still relatively inefficient. Researchers are hoping that if they can use quantum mechanics to work out whats going on inside that reaction, they could discover new ways to make the process much more efficient.

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Quantum Computing Explained – WIRED UK

Quantum computing: A simple introduction – Explain that Stuff

by Chris Woodford. Last updated: March 9, 2018.

How can you get more and more out of less and less? The smaller computers get, the more powerful they seem to become: there’s more number-crunching ability in a 21st-century cellphone than you’d have found in a room-sized, military computer 50 years ago. Yet, despitesuch amazing advances, there are still plenty of complex problemsthat are beyond the reach of even the world’s most powerfulcomputersand there’s no guarantee we’ll ever be able to tacklethem. One problem is that the basic switching and memory units ofcomputers, known as transistors, are now approaching the point wherethey’ll soon be as small as individual atoms. If we want computersthat are smaller and more powerful than today’s, we’ll soon need todo our computing in a radically different way. Entering the realm ofatoms opens up powerful new possibilities in the shape of quantumcomputing, with processors that could work millions of timesfaster than the ones we use today. Sounds amazing, but the trouble isthat quantum computing is hugely more complex than traditionalcomputing and operates in the Alice in Wonderland world of quantumphysics, where the “classical,” sensible, everyday laws of physics no longer apply. What isquantum computing and how does it work? Let’s take a closer look!

Photo: Quantum computing means storing and processing information using individual atoms, ions, electrons, or photons. On the plus side, this opens up the possibility of faster computers, but the drawback is the greater complexity of designing computers that can operate in the weird world of quantum physics.

You probably think of a computer as a neat little gadget that sits on your lap and lets you send emails, shop online, chat to your friends, or play gamesbut it’s much moreand much lessthan that. It’s more, because it’s a completely general-purposemachine: you can make it do virtually anything you like. It’sless, because inside it’s little more than an extremely basiccalculator, following a prearranged set of instructions called aprogram. Like the Wizard of Oz, the amazing things you see in front of youconceal some pretty mundane stuff under the covers.

Photo: This is what one transistor from a typical radio circuit board looks like. In computers, the transistors are much smaller than this and millions of them are packaged together onto microchips.

Conventional computers have two tricks that they do really well: they can storenumbers in memory and they can process stored numbers with simple mathematical operations (like add and subtract). They can do more complex things by stringing together the simple operations into a series called an algorithm (multiplying can bedone as a series of additions, for example). Both of a computer’s keytricksstorage and processingare accomplished using switchescalled transistors, which are like microscopic versions of theswitches you have on your wall for turning on and off the lights. Atransistor can either be on or off, just as a light can either be litor unlit. If it’s on, we can use a transistor to store a number one(1); if it’s off, it stores a number zero (0). Long strings of onesand zeros can be used to store any number, letter, or symbol using acode based on binary (so computers store an upper-case letter A as1000001 and a lower-case one as 01100001). Each of the zeros or ones is called a binary digit (or bit) and, with a string of eight bits, you can store 255 differentcharacters (such as A-Z, a-z, 0-9, and most common symbols).Computers calculate by using circuits called logic gates,which are made from a number of transistors connected together. Logicgates compare patterns of bits, stored in temporary memories calledregisters, and then turn them into new patterns of bitsandthat’s the computer equivalent of what our human brains would calladdition, subtraction, or multiplication. In physical terms, thealgorithm that performs a particular calculation takes the form of anelectronic circuit made from a number of logic gates, with the output from one gate feeding in as the input to the next.

The trouble with conventional computers is that they depend onconventional transistors. This might not sound like a problem if yougo by the amazing progress made in electronics over the last fewdecades. When the transistor was invented, back in 1947, the switchit replaced (which was called the vacuum tube) was about asbig as one of your thumbs. Now, a state-of-the-art microprocessor(single-chip computer) packs hundreds of millions (and up to twobillion) transistors onto a chip of silicon the size of yourfingernail! Chips like these, which are called integrated circuits, are an incredible feat of miniaturization. Back in the1960s, Intel co-founder Gordon Moore realized that the power ofcomputers doubles roughly 18 monthsand it’s been doing so eversince. This apparently unshakeable trend is known as Moore’s Law.

Photo: This memory chip from a typical USB stick contains an integrated circuit that can store 512 megabytes of data. That’s roughly 500 million characters (536,870,912 to be exact), each of which needs eight binary digitsso we’re talking about 4 billion (4,000 million) transistors in all (4,294,967,296 if you’re being picky) packed into an area the size of a postage stamp!

It sounds amazing, and it is, but it misses the point. The moreinformation you need to store, the more binary ones and zerosandtransistorsyou need to do it. Since most conventional computers canonly do one thing at a time, the more complex the problem you wantthem to solve, the more steps they’ll need to take and the longerthey’ll need to do it. Some computing problems are so complex thatthey need more computing power and time than any modern machine couldreasonably supply; computer scientists call those intractableproblems.

As Moore’s Law advances, so the number of intractable problemsdiminishes: computers get more powerful and we can do more with them.The trouble is, transistors are just about as small as we can makethem: we’re getting to the point where the laws of physics seem likelyto put a stop to Moore’s Law. Unfortunately, there are still hugelydifficult computing problems we can’t tackle because even the mostpowerful computers find them intractable. That’s one of the reasonswhy people are now getting interested in quantum computing.

Things on a very small scale behave like nothing you have any direct experience about… or like anything that you have ever seen.

Richard Feynman

Quantum theory is the branch of physics that deals with the world ofatoms and the smaller (subatomic) particles inside them. You mightthink atoms behave the same way as everything else in the world, intheir own tiny little waybut that’s not true: on the atomic scale, the rules change and the “classical” laws of physics we take for granted in our everyday world no longer automatically apply. As Richard P. Feynman,one of the greatest physicists of the 20th century, once put it: “Things on a very small scale behave like nothing you have any direct experience about… or like anything that you have ever seen.” (Six Easy Pieces, p116.)

If you’ve studied light, you may already know a bit about quantumtheory. You might know that a beam of light sometimes behaves asthough it’s made up of particles (like a steady stream ofcannonballs), and sometimes as though it’s waves of energy ripplingthrough space (a bit like waves on the sea). That’s called wave-particle dualityand it’s one of the ideas that comes to us from quantum theory. It’s hard to grasp thatsomething can be two things at oncea particle and awavebecause it’s totally alien to our everyday experience: a car isnot simultaneously a bicycle and a bus. In quantum theory, however,that’s just the kind of crazy thing that can happen. The most striking example of this is the baffling riddle known as Schrdinger’s cat. Briefly, in the weird world ofquantum theory, we can imagine a situation where something like a catcould be alive and dead at the same time!

What does all this have to do with computers? Suppose we keep on pushingMoore’s Lawkeep on making transistors smaller until they get to thepoint where they obey not the ordinary laws of physics (likeold-style transistors) but the more bizarre laws of quantummechanics. The question is whether computers designed this way can dothings our conventional computers can’t. If we can predictmathematically that they might be able to, can we actually make themwork like that in practice?

People have been asking those questions for several decades.Among the first were IBM research physicists Rolf Landauer and Charles H. Bennett. Landauer opened the door for quantumcomputing in the 1960s when he proposed that information is a physical entitythat could be manipulated according to the laws of physics.One important consequence of this is that computers waste energy manipulating the bits inside them(which is partly why computers use so much energy and get so hot, even though they appear to be doingnot very much at all). In the 1970s, building on Landauer’s work, Bennett showed how a computer could circumventthis problem by working in a “reversible” way, implying that a quantum computer couldcarry out massively complex computations without using massive amounts of energy.In 1981, physicist Paul Benioff from Argonne National Laboratory tried to envisage a basic machine that would work in a similar way to an ordinary computer but according to the principlesof quantum physics. The following year, Richard Feynman sketched out roughly how a machine using quantum principles could carry out basiccomputations. A few years later, Oxford University’s David Deutsch(one of the leading lights in quantum computing) outlined thetheoretical basis of a quantum computer in more detail. How did thesegreat scientists imagine that quantum computers might work?

The key features of an ordinary computerbits, registers, logic gates,algorithms, and so onhave analogous features in a quantum computer.Instead of bits, a quantum computer has quantum bits or qubits,which work in a particularly intriguing way. Where a bit can storeeither a zero or a 1, a qubit can store a zero, a one, bothzero and one, or an infinite number of values in betweenandbe in multiple states (store multiple values) at the same time!If that sounds confusing, think back to light being a particle anda wave at the same time, Schrdinger’s cat being alive and dead, or acar being a bicycle and a bus. A gentler way to think of the numbersqubits store is through the physics concept of superposition(where two waves add to make a third one that contains both of theoriginals). If you blow on something like a flute, the pipe fills upwith a standing wave: a wave made up of a fundamental frequency (thebasic note you’re playing) and lots of overtones or harmonics(higher-frequency multiples of the fundamental). The wave inside thepipe contains all these waves simultaneously: they’re added togetherto make a combined wave that includes them all. Qubits usesuperposition to represent multiple states (multiple numeric values)simultaneously in a similar way.

Just as a quantum computer can store multiple numbers at once, so it canprocess them simultaneously. Instead of working in serial (doing aseries of things one at a time in a sequence), it can work inparallel (doing multiple things at the same time). Only when youtry to find out what state it’s actually in at any given moment(by measuring it, in other words) does it “collapse” into one of its possible statesandthat gives you the answer to your problem. Estimates suggesta quantum computer’s ability to work in parallel would make it millions of times faster thanany conventional computer… if only we could build it! So howwould we do that?

In reality, qubits would have to be stored by atoms, ions (atoms withtoo many or too few electrons), or even smaller things such as electronsand photons (energy packets), so a quantum computer would be almost like a table-topversion of the kind of particle physics experiments they do atFermilab or CERN. Now you wouldn’t be racing particles round giantloops and smashing them together, but you would need mechanisms forcontaining atoms, ions, or subatomic particles, for putting them into certainstates (so you can store information), knocking them into other states (so you canmake them process information), and figuring out what their states are after particularoperations have been performed.

Photo: A single atom can be trapped in an optical cavitythe space between mirrorsand controlled by precise pulses from laser beams.

In practice, there are lots of possible ways of containing atoms and changing their states usinglaser beams, electromagneticfields, radio waves, and an assortment of other techniques.One method is to make qubits usingquantum dots, which are nanoscopically tiny particles of semiconductors inside which individual charge carriers, electrons and holes (missing electrons), can be controlled. Another methodmakes qubits from what are called ion traps: you add or take awayelectrons from an atom to make an ion, hold it steady in a kind of laser spotlight(so it’s locked in place like a nanoscopic rabbit dancing in a very bright headlight),and then flip it into different states with laser pulses. In another technique,the qubits are photons inside optical cavities (spaces betweenextremely tiny mirrors). Don’t worry if you don’t understand; not many people do. Since the entirefield of quantum computing is still largely abstract and theoretical, the only thing we really need to knowis that qubits are stored by atoms or other quantum-scale particles that canexist in different states and be switched between them.

Although people often assume that quantum computers must automatically bebetter than conventional ones, that’s by no means certain. So far,just about the only thing we know for certain that a quantum computer could do better than anormal one is factorisation: finding two unknown prime numbers that,when multiplied together, give a third, known number. In 1994,while working at Bell Laboratories, mathematician Peter Shor demonstrated an algorithm that a quantum computercould follow to find the “prime factors” of a large number, whichwould speed up the problem enormously. Shor’s algorithm reallyexcited interest in quantum computing because virtually every moderncomputer (and every secure, online shopping and banking website) usespublic-key encryption technology based on the virtual impossibility of finding prime factors quickly (it is, in other words, essentiallyan “intractable” computer problem). If quantum computers couldindeed factor large numbers quickly, today’s online security could berendered obsolete at a stroke. But what goes around comes around,and some researchers believe quantum technology will lead tomuch stronger forms of encryption.(In 2017, Chinese researchers demonstrated for the first timehow quantum encryption could be used to make a very secure video callfrom Beijing to Vienna.)

Does that mean quantum computers are better than conventional ones? Notexactly. Apart from Shor’s algorithm, and a search method called Grover’s algorithm, hardly any other algorithms have been discovered that wouldbe better performed by quantum methods. Given enough time andcomputing power, conventional computers should still be able to solveany problem that quantum computers could solve, eventually. Inother words, it remains to be proven that quantum computers aregenerally superior to conventional ones, especially given the difficulties ofactually building them. Who knows how conventional computers might advancein the next 50 years, potentially making the idea of quantum computers irrelevantand even absurd.

Photo: Quantum dots are probably best known as colorful nanoscale crystals, but they can also be used as qubits in quantum computers). Photo courtesy of Argonne National Laboratory.

Three decades after they were first proposed, quantum computers remainlargely theoretical. Even so, there’s been some encouraging progresstoward realizing a quantum machine. There were two impressivebreakthroughs in 2000. First, Isaac Chuang (now an MIT professor, but then working at IBM’sAlmaden Research Center) used five fluorine atoms to make a crude,five-qubit quantum computer. The same year, researchers at LosAlamos National Laboratory figured out how to make a seven-qubitmachine using a drop of liquid. Five years later, researchers at theUniversity of Innsbruck added an extra qubit and produced the firstquantum computer that could manipulate a qubyte (eight qubits).

These were tentative but important first steps.Over the next few years, researchers announced more ambitious experiments, addingprogressively greater numbers of qubits. By 2011, a pioneering Canadiancompany called D-Wave Systems announced in Nature that it had produced a 128-qubitmachine; the announcement proved highly controversialand there was a lot of debate over whether the company’s machines had really demonstrated quantum behavior.Three years later, Google announced that it was hiring a team of academics (including University of Californiaat Santa Barbara physicist John Martinis) to develop its own quantum computers based on D-Wave’s approach.In March 2015, the Google team announced they were “a step closer to quantum computation,” having developeda new way for qubits to detect and protect against errors.In 2016, MIT’s Isaac Chuang and scientists from the University of Innsbruckunveiled a five-qubit, ion-trap quantum computer that could calculate the factors of 15; one day, a scaled-up version of this machine mightevolve into the long-promised, fully fledged encryption buster.

There’s no doubt that these are hugely important advances.and the signs are growing steadily more encouraging that quantumtechnology will eventually deliver a computing revolution.In December 2017, Microsoft unveiled a completequantum development kit, including a new computer language, Q#, developed specifically forquantum applications. In early 2018,D-wave announced plans to start rolling out quantum power to acloud computing platform.A few weeks later, Google announced Bristlecone, a quantum processorbased on a 72-qubit array, that might, one day, form the cornerstone of a quantum computer that could tackle real-world problems.All very exciting! Even so, it’s early days for the whole field, and mostresearchers agree that we’re unlikely to see practical quantumcomputers appearing for some yearsand more likely several decades.

View original post here:

Quantum computing: A simple introduction – Explain that Stuff

What is Quantum Computing? Webopedia Definition

Main TERM Q

First proposed in the 1970s, quantum computing relies on quantum physics by taking advantage of certain quantum physics properties of atoms or nuclei that allow them to work together as quantum bits, or qubits, to be the computer’s processor and memory. By interacting with each other while being isolated from the external environment, qubits can perform certain calculations exponentially faster than conventional computers.

Qubits do not rely on the traditional binary nature of computing. While traditional computers encode information into bits using binary numbers, either a 0 or 1, and can only do calculations on one set of numbers at once, quantum computers encode information as a series of quantum-mechanical states such as spin directions of electrons or polarization orientations of a photon that might represent a 1 or a 0, might represent a combination of the two or might represent a number expressing that the state of the qubit is somewhere between 1 and 0, or a superposition of many different numbers at once.

A quantum computer can do an arbitrary reversible classical computation on all the numbers simultaneously, which a binary system cannot do, and also has some ability to produce interference between various different numbers. By doing a computation on many different numbers at once, then interfering the results to get a single answer, a quantum computer has the potential to be much more powerful than a classical computer of the same size. In using only a single processing unit, a quantum computer can naturally perform myriad operations in parallel.

Quantum computing is not well suited for tasks such as word processing and email, but it is ideal for tasks such as cryptography and modeling and indexing very large databases.

Microsoft: Quantum Computing 101

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See the article here:

What is Quantum Computing? Webopedia Definition

Quantum Computing Explained – WIRED UK

Ray Orange

Google, IBM and a handful of startups are racing to create the next generation of supercomputers. Quantum computers, if they ever get started, will help us solve problems, like modelling complex chemical processes, that our existing computers can’t even scratch the surface of.

But the quantum future isn’t going to come easily, and there’s no knowing what it’ll look like when it does arrive. At the moment, companies and researchers are using a handful of different approaches to try and build the most powerful computers the world has ever seen. Here’s everything you need to know about the coming quantum revolution.

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

D-Wave

“The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called ‘entangled states’,” says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states at either of the two poles of the sphere a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something its calling quantum supremacy with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldnt hope to simulate, isnt exactly a widely accepted term within the quantum community. Those sceptical of Googles quantum project or at least the way it talks about quantum computing argue that supremacy is essentially an arbitrary goal set by Google to make it look like its making strides in quantum when really its just meeting self-imposed targets.

Whether its an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesnt necessarily mean theyve cracked supremacy and definitely doesnt mean that theyve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers dont consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, its likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, its possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers arent very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope theyll be able to use quantum simulations to design entirely new molecules for use in medicine. But the holy grail for quantum chemists is to be able to model the Haber-Bosch process a way of artificially producing ammonia that is still relatively inefficient. Researchers are hoping that if they can use quantum mechanics to work out whats going on inside that reaction, they could discover new ways to make the process much more efficient.

Read more:

Quantum Computing Explained – WIRED UK

What is Quantum Computing? Webopedia Definition

Main TERM Q

First proposed in the 1970s, quantum computing relies on quantum physics by taking advantage of certain quantum physics properties of atoms or nuclei that allow them to work together as quantum bits, or qubits, to be the computer’s processor and memory. By interacting with each other while being isolated from the external environment, qubits can perform certain calculations exponentially faster than conventional computers.

Qubits do not rely on the traditional binary nature of computing. While traditional computers encode information into bits using binary numbers, either a 0 or 1, and can only do calculations on one set of numbers at once, quantum computers encode information as a series of quantum-mechanical states such as spin directions of electrons or polarization orientations of a photon that might represent a 1 or a 0, might represent a combination of the two or might represent a number expressing that the state of the qubit is somewhere between 1 and 0, or a superposition of many different numbers at once.

A quantum computer can do an arbitrary reversible classical computation on all the numbers simultaneously, which a binary system cannot do, and also has some ability to produce interference between various different numbers. By doing a computation on many different numbers at once, then interfering the results to get a single answer, a quantum computer has the potential to be much more powerful than a classical computer of the same size. In using only a single processing unit, a quantum computer can naturally perform myriad operations in parallel.

Quantum computing is not well suited for tasks such as word processing and email, but it is ideal for tasks such as cryptography and modeling and indexing very large databases.

Microsoft: Quantum Computing 101

Stay up to date on the latest developments in Internet terminology with a free weekly newsletter from Webopedia. Join to subscribe now.

Read the original post:

What is Quantum Computing? Webopedia Definition

What are quantum computers and how do they work? WIRED …

Ray Orange

Google, IBM and a handful of startups are racing to create the next generation of supercomputers. Quantum computers, if they ever get started, will help us solve problems, like modelling complex chemical processes, that our existing computers can’t even scratch the surface of.

But the quantum future isn’t going to come easily, and there’s no knowing what it’ll look like when it does arrive. At the moment, companies and researchers are using a handful of different approaches to try and build the most powerful computers the world has ever seen. Here’s everything you need to know about the coming quantum revolution.

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

D-Wave

“The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called ‘entangled states’,” says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states at either of the two poles of the sphere a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something its calling quantum supremacy with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldnt hope to simulate, isnt exactly a widely accepted term within the quantum community. Those sceptical of Googles quantum project or at least the way it talks about quantum computing argue that supremacy is essentially an arbitrary goal set by Google to make it look like its making strides in quantum when really its just meeting self-imposed targets.

Whether its an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesnt necessarily mean theyve cracked supremacy and definitely doesnt mean that theyve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers dont consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, its likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, its possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers arent very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope theyll be able to use quantum simulations to design entirely new molecules for use in medicine. But the holy grail for quantum chemists is to be able to model the Haber-Bosch process a way of artificially producing ammonia that is still relatively inefficient. Researchers are hoping that if they can use quantum mechanics to work out whats going on inside that reaction, they could discover new ways to make the process much more efficient.

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What are quantum computers and how do they work? WIRED …

Quantum computing: A simple introduction – Explain that Stuff

by Chris Woodford. Last updated: March 9, 2018.

How can you get more and more out of less and less? The smaller computers get, the more powerful they seem to become: there’s more number-crunching ability in a 21st-century cellphone than you’d have found in a room-sized, military computer 50 years ago. Yet, despitesuch amazing advances, there are still plenty of complex problemsthat are beyond the reach of even the world’s most powerfulcomputersand there’s no guarantee we’ll ever be able to tacklethem. One problem is that the basic switching and memory units ofcomputers, known as transistors, are now approaching the point wherethey’ll soon be as small as individual atoms. If we want computersthat are smaller and more powerful than today’s, we’ll soon need todo our computing in a radically different way. Entering the realm ofatoms opens up powerful new possibilities in the shape of quantumcomputing, with processors that could work millions of timesfaster than the ones we use today. Sounds amazing, but the trouble isthat quantum computing is hugely more complex than traditionalcomputing and operates in the Alice in Wonderland world of quantumphysics, where the “classical,” sensible, everyday laws of physics no longer apply. What isquantum computing and how does it work? Let’s take a closer look!

Photo: Quantum computing means storing and processing information using individual atoms, ions, electrons, or photons. On the plus side, this opens up the possibility of faster computers, but the drawback is the greater complexity of designing computers that can operate in the weird world of quantum physics.

You probably think of a computer as a neat little gadget that sits on your lap and lets you send emails, shop online, chat to your friends, or play gamesbut it’s much moreand much lessthan that. It’s more, because it’s a completely general-purposemachine: you can make it do virtually anything you like. It’sless, because inside it’s little more than an extremely basiccalculator, following a prearranged set of instructions called aprogram. Like the Wizard of Oz, the amazing things you see in front of youconceal some pretty mundane stuff under the covers.

Photo: This is what one transistor from a typical radio circuit board looks like. In computers, the transistors are much smaller than this and millions of them are packaged together onto microchips.

Conventional computers have two tricks that they do really well: they can storenumbers in memory and they can process stored numbers with simple mathematical operations (like add and subtract). They can do more complex things by stringing together the simple operations into a series called an algorithm (multiplying can bedone as a series of additions, for example). Both of a computer’s keytricksstorage and processingare accomplished using switchescalled transistors, which are like microscopic versions of theswitches you have on your wall for turning on and off the lights. Atransistor can either be on or off, just as a light can either be litor unlit. If it’s on, we can use a transistor to store a number one(1); if it’s off, it stores a number zero (0). Long strings of onesand zeros can be used to store any number, letter, or symbol using acode based on binary (so computers store an upper-case letter A as1000001 and a lower-case one as 01100001). Each of the zeros or ones is called a binary digit (or bit) and, with a string of eight bits, you can store 255 differentcharacters (such as A-Z, a-z, 0-9, and most common symbols).Computers calculate by using circuits called logic gates,which are made from a number of transistors connected together. Logicgates compare patterns of bits, stored in temporary memories calledregisters, and then turn them into new patterns of bitsandthat’s the computer equivalent of what our human brains would calladdition, subtraction, or multiplication. In physical terms, thealgorithm that performs a particular calculation takes the form of anelectronic circuit made from a number of logic gates, with the output from one gate feeding in as the input to the next.

The trouble with conventional computers is that they depend onconventional transistors. This might not sound like a problem if yougo by the amazing progress made in electronics over the last fewdecades. When the transistor was invented, back in 1947, the switchit replaced (which was called the vacuum tube) was about asbig as one of your thumbs. Now, a state-of-the-art microprocessor(single-chip computer) packs hundreds of millions (and up to twobillion) transistors onto a chip of silicon the size of yourfingernail! Chips like these, which are called integrated circuits, are an incredible feat of miniaturization. Back in the1960s, Intel co-founder Gordon Moore realized that the power ofcomputers doubles roughly 18 monthsand it’s been doing so eversince. This apparently unshakeable trend is known as Moore’s Law.

Photo: This memory chip from a typical USB stick contains an integrated circuit that can store 512 megabytes of data. That’s roughly 500 million characters (536,870,912 to be exact), each of which needs eight binary digitsso we’re talking about 4 billion (4,000 million) transistors in all (4,294,967,296 if you’re being picky) packed into an area the size of a postage stamp!

It sounds amazing, and it is, but it misses the point. The moreinformation you need to store, the more binary ones and zerosandtransistorsyou need to do it. Since most conventional computers canonly do one thing at a time, the more complex the problem you wantthem to solve, the more steps they’ll need to take and the longerthey’ll need to do it. Some computing problems are so complex thatthey need more computing power and time than any modern machine couldreasonably supply; computer scientists call those intractableproblems.

As Moore’s Law advances, so the number of intractable problemsdiminishes: computers get more powerful and we can do more with them.The trouble is, transistors are just about as small as we can makethem: we’re getting to the point where the laws of physics seem likelyto put a stop to Moore’s Law. Unfortunately, there are still hugelydifficult computing problems we can’t tackle because even the mostpowerful computers find them intractable. That’s one of the reasonswhy people are now getting interested in quantum computing.

Things on a very small scale behave like nothing you have any direct experience about… or like anything that you have ever seen.

Richard Feynman

Quantum theory is the branch of physics that deals with the world ofatoms and the smaller (subatomic) particles inside them. You mightthink atoms behave the same way as everything else in the world, intheir own tiny little waybut that’s not true: on the atomic scale, the rules change and the “classical” laws of physics we take for granted in our everyday world no longer automatically apply. As Richard P. Feynman,one of the greatest physicists of the 20th century, once put it: “Things on a very small scale behave like nothing you have any direct experience about… or like anything that you have ever seen.” (Six Easy Pieces, p116.)

If you’ve studied light, you may already know a bit about quantumtheory. You might know that a beam of light sometimes behaves asthough it’s made up of particles (like a steady stream ofcannonballs), and sometimes as though it’s waves of energy ripplingthrough space (a bit like waves on the sea). That’s called wave-particle dualityand it’s one of the ideas that comes to us from quantum theory. It’s hard to grasp thatsomething can be two things at oncea particle and awavebecause it’s totally alien to our everyday experience: a car isnot simultaneously a bicycle and a bus. In quantum theory, however,that’s just the kind of crazy thing that can happen. The most striking example of this is the baffling riddle known as Schrdinger’s cat. Briefly, in the weird world ofquantum theory, we can imagine a situation where something like a catcould be alive and dead at the same time!

What does all this have to do with computers? Suppose we keep on pushingMoore’s Lawkeep on making transistors smaller until they get to thepoint where they obey not the ordinary laws of physics (likeold-style transistors) but the more bizarre laws of quantummechanics. The question is whether computers designed this way can dothings our conventional computers can’t. If we can predictmathematically that they might be able to, can we actually make themwork like that in practice?

People have been asking those questions for several decades.Among the first were IBM research physicists Rolf Landauer and Charles H. Bennett. Landauer opened the door for quantumcomputing in the 1960s when he proposed that information is a physical entitythat could be manipulated according to the laws of physics.One important consequence of this is that computers waste energy manipulating the bits inside them(which is partly why computers use so much energy and get so hot, even though they appear to be doingnot very much at all). In the 1970s, building on Landauer’s work, Bennett showed how a computer could circumventthis problem by working in a “reversible” way, implying that a quantum computer couldcarry out massively complex computations without using massive amounts of energy.In 1981, physicist Paul Benioff from Argonne National Laboratory tried to envisage a basic machine that would work in a similar way to an ordinary computer but according to the principlesof quantum physics. The following year, Richard Feynman sketched out roughly how a machine using quantum principles could carry out basiccomputations. A few years later, Oxford University’s David Deutsch(one of the leading lights in quantum computing) outlined thetheoretical basis of a quantum computer in more detail. How did thesegreat scientists imagine that quantum computers might work?

The key features of an ordinary computerbits, registers, logic gates,algorithms, and so onhave analogous features in a quantum computer.Instead of bits, a quantum computer has quantum bits or qubits,which work in a particularly intriguing way. Where a bit can storeeither a zero or a 1, a qubit can store a zero, a one, bothzero and one, or an infinite number of values in betweenandbe in multiple states (store multiple values) at the same time!If that sounds confusing, think back to light being a particle anda wave at the same time, Schrdinger’s cat being alive and dead, or acar being a bicycle and a bus. A gentler way to think of the numbersqubits store is through the physics concept of superposition(where two waves add to make a third one that contains both of theoriginals). If you blow on something like a flute, the pipe fills upwith a standing wave: a wave made up of a fundamental frequency (thebasic note you’re playing) and lots of overtones or harmonics(higher-frequency multiples of the fundamental). The wave inside thepipe contains all these waves simultaneously: they’re added togetherto make a combined wave that includes them all. Qubits usesuperposition to represent multiple states (multiple numeric values)simultaneously in a similar way.

Just as a quantum computer can store multiple numbers at once, so it canprocess them simultaneously. Instead of working in serial (doing aseries of things one at a time in a sequence), it can work inparallel (doing multiple things at the same time). Only when youtry to find out what state it’s actually in at any given moment(by measuring it, in other words) does it “collapse” into one of its possible statesandthat gives you the answer to your problem. Estimates suggesta quantum computer’s ability to work in parallel would make it millions of times faster thanany conventional computer… if only we could build it! So howwould we do that?

In reality, qubits would have to be stored by atoms, ions (atoms withtoo many or too few electrons), or even smaller things such as electronsand photons (energy packets), so a quantum computer would be almost like a table-topversion of the kind of particle physics experiments they do atFermilab or CERN. Now you wouldn’t be racing particles round giantloops and smashing them together, but you would need mechanisms forcontaining atoms, ions, or subatomic particles, for putting them into certainstates (so you can store information), knocking them into other states (so you canmake them process information), and figuring out what their states are after particularoperations have been performed.

Photo: A single atom can be trapped in an optical cavitythe space between mirrorsand controlled by precise pulses from laser beams.

In practice, there are lots of possible ways of containing atoms and changing their states usinglaser beams, electromagneticfields, radio waves, and an assortment of other techniques.One method is to make qubits usingquantum dots, which are nanoscopically tiny particles of semiconductors inside which individual charge carriers, electrons and holes (missing electrons), can be controlled. Another methodmakes qubits from what are called ion traps: you add or take awayelectrons from an atom to make an ion, hold it steady in a kind of laser spotlight(so it’s locked in place like a nanoscopic rabbit dancing in a very bright headlight),and then flip it into different states with laser pulses. In another technique,the qubits are photons inside optical cavities (spaces betweenextremely tiny mirrors). Don’t worry if you don’t understand; not many people do. Since the entirefield of quantum computing is still largely abstract and theoretical, the only thing we really need to knowis that qubits are stored by atoms or other quantum-scale particles that canexist in different states and be switched between them.

Although people often assume that quantum computers must automatically bebetter than conventional ones, that’s by no means certain. So far,just about the only thing we know for certain that a quantum computer could do better than anormal one is factorisation: finding two unknown prime numbers that,when multiplied together, give a third, known number. In 1994,while working at Bell Laboratories, mathematician Peter Shor demonstrated an algorithm that a quantum computercould follow to find the “prime factors” of a large number, whichwould speed up the problem enormously. Shor’s algorithm reallyexcited interest in quantum computing because virtually every moderncomputer (and every secure, online shopping and banking website) usespublic-key encryption technology based on the virtual impossibility of finding prime factors quickly (it is, in other words, essentiallyan “intractable” computer problem). If quantum computers couldindeed factor large numbers quickly, today’s online security could berendered obsolete at a stroke. But what goes around comes around,and some researchers believe quantum technology will lead tomuch stronger forms of encryption.(In 2017, Chinese researchers demonstrated for the first timehow quantum encryption could be used to make a very secure video callfrom Beijing to Vienna.)

Does that mean quantum computers are better than conventional ones? Notexactly. Apart from Shor’s algorithm, and a search method called Grover’s algorithm, hardly any other algorithms have been discovered that wouldbe better performed by quantum methods. Given enough time andcomputing power, conventional computers should still be able to solveany problem that quantum computers could solve, eventually. Inother words, it remains to be proven that quantum computers aregenerally superior to conventional ones, especially given the difficulties ofactually building them. Who knows how conventional computers might advancein the next 50 years, potentially making the idea of quantum computers irrelevantand even absurd.

Photo: Quantum dots are probably best known as colorful nanoscale crystals, but they can also be used as qubits in quantum computers). Photo courtesy of Argonne National Laboratory.

Three decades after they were first proposed, quantum computers remainlargely theoretical. Even so, there’s been some encouraging progresstoward realizing a quantum machine. There were two impressivebreakthroughs in 2000. First, Isaac Chuang (now an MIT professor, but then working at IBM’sAlmaden Research Center) used five fluorine atoms to make a crude,five-qubit quantum computer. The same year, researchers at LosAlamos National Laboratory figured out how to make a seven-qubitmachine using a drop of liquid. Five years later, researchers at theUniversity of Innsbruck added an extra qubit and produced the firstquantum computer that could manipulate a qubyte (eight qubits).

These were tentative but important first steps.Over the next few years, researchers announced more ambitious experiments, addingprogressively greater numbers of qubits. By 2011, a pioneering Canadiancompany called D-Wave Systems announced in Nature that it had produced a 128-qubitmachine; the announcement proved highly controversialand there was a lot of debate over whether the company’s machines had really demonstrated quantum behavior.Three years later, Google announced that it was hiring a team of academics (including University of Californiaat Santa Barbara physicist John Martinis) to develop its own quantum computers based on D-Wave’s approach.In March 2015, the Google team announced they were “a step closer to quantum computation,” having developeda new way for qubits to detect and protect against errors.In 2016, MIT’s Isaac Chuang and scientists from the University of Innsbruckunveiled a five-qubit, ion-trap quantum computer that could calculate the factors of 15; one day, a scaled-up version of this machine mightevolve into the long-promised, fully fledged encryption buster.

There’s no doubt that these are hugely important advances.and the signs are growing steadily more encouraging that quantumtechnology will eventually deliver a computing revolution.In December 2017, Microsoft unveiled a completequantum development kit, including a new computer language, Q#, developed specifically forquantum applications. In early 2018,D-wave announced plans to start rolling out quantum power to acloud computing platform.A few weeks later, Google announced Bristlecone, a quantum processorbased on a 72-qubit array, that might, one day, form the cornerstone of a quantum computer that could tackle real-world problems.All very exciting! Even so, it’s early days for the whole field, and mostresearchers agree that we’re unlikely to see practical quantumcomputers appearing for some yearsand more likely several decades.

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Quantum computing: A simple introduction – Explain that Stuff

What is Quantum Computing? Webopedia Definition

Main TERM Q

First proposed in the 1970s, quantum computing relies on quantum physics by taking advantage of certain quantum physics properties of atoms or nuclei that allow them to work together as quantum bits, or qubits, to be the computer’s processor and memory. By interacting with each other while being isolated from the external environment, qubits can perform certain calculations exponentially faster than conventional computers.

Qubits do not rely on the traditional binary nature of computing. While traditional computers encode information into bits using binary numbers, either a 0 or 1, and can only do calculations on one set of numbers at once, quantum computers encode information as a series of quantum-mechanical states such as spin directions of electrons or polarization orientations of a photon that might represent a 1 or a 0, might represent a combination of the two or might represent a number expressing that the state of the qubit is somewhere between 1 and 0, or a superposition of many different numbers at once.

A quantum computer can do an arbitrary reversible classical computation on all the numbers simultaneously, which a binary system cannot do, and also has some ability to produce interference between various different numbers. By doing a computation on many different numbers at once, then interfering the results to get a single answer, a quantum computer has the potential to be much more powerful than a classical computer of the same size. In using only a single processing unit, a quantum computer can naturally perform myriad operations in parallel.

Quantum computing is not well suited for tasks such as word processing and email, but it is ideal for tasks such as cryptography and modeling and indexing very large databases.

Microsoft: Quantum Computing 101

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What is Quantum Computing? Webopedia Definition

Quantum Computing Explained – WIRED UK

Ray Orange

Google, IBM and a handful of startups are racing to create the next generation of supercomputers. Quantum computers, if they ever get started, will help us solve problems, like modelling complex chemical processes, that our existing computers can’t even scratch the surface of.

But the quantum future isn’t going to come easily, and there’s no knowing what it’ll look like when it does arrive. At the moment, companies and researchers are using a handful of different approaches to try and build the most powerful computers the world has ever seen. Here’s everything you need to know about the coming quantum revolution.

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

D-Wave

“The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called ‘entangled states’,” says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states at either of the two poles of the sphere a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

Until recently, it seemed like Google was leading the pack when it came to creating a quantum computer that could surpass the abilities of conventional computers. In a Nature article published in March 2017, the search giant set out ambitious plans to commercialise quantum technology in the next five years. Shortly after that, Google said it intended to achieve something its calling quantum supremacy with a 49-qubit computer by the end of 2017.

Now, quantum supremacy, which roughly refers to the point where a quantum computer can crunch sums that a conventional computer couldnt hope to simulate, isnt exactly a widely accepted term within the quantum community. Those sceptical of Googles quantum project or at least the way it talks about quantum computing argue that supremacy is essentially an arbitrary goal set by Google to make it look like its making strides in quantum when really its just meeting self-imposed targets.

Whether its an arbitrary goal or not, Google was pipped to the supremacy post by IBM in November 2017, when the company announced it had built a 50-qubit quantum computer. Even that, however, was far from stable, as the system could only hold its quantum microstate for 90 microseconds, a record, but far from the times needed to make quantum computing practically viable. Just because IBM has built a 50-qubit system, however, doesnt necessarily mean theyve cracked supremacy and definitely doesnt mean that theyve created a quantum computer that is anywhere near ready for practical use.

Where IBM has gone further than Google, however, is making quantum computers commercially available. Since 2016, it has offered researchers the chance to run experiments on a five-qubit quantum computer via the cloud and at the end of 2017 started making its 20-qubit system available online too.

But quantum computing is by no means a two-horse race. Californian startup Rigetti is focusing on the stability of its own systems rather than just the number of qubits and it could be the first to build a quantum computer that people can actually use. D-Wave, a company based in Vancouver, Canada, has already created what it is calling a 2,000-qubit system although many researchers dont consider the D-wave systems to be true quantum computers. Intel, too, has skin in the game. In February 2018 the company announced that it had found a way of fabricating quantum chips from silicon, which would make it much easier to produce chips using existing manufacturing methods.

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, its likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, its possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers arent very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope theyll be able to use quantum simulations to design entirely new molecules for use in medicine. But the holy grail for quantum chemists is to be able to model the Haber-Bosch process a way of artificially producing ammonia that is still relatively inefficient. Researchers are hoping that if they can use quantum mechanics to work out whats going on inside that reaction, they could discover new ways to make the process much more efficient.

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Quantum Computing Explained – WIRED UK

Is Quantum Computing an Existential Threat to Blockchain …

Amid steep gains in value and wild headlines, its easy to forget cryptocurrencies and blockchain arent yet mainstream. Even so, fans of the technology believe blockchain has too much potential not to have a major sustained impact in the future.

But as is usually the case when pondering whats ahead, nothing is certain.

When considering existential threats to blockchain and cryptocurrencies, people generally focus on increased regulation. And this makes sense. In the medium term, greater regulation may stand in the way of cryptocurrencies and wider mainstream adoption. However, there might be a bigger threat further out on the horizon.

Much of blockchains allure arises from its security benefits. The tech allows a ledger of transactions to be distributed between a large network of computers. No single user can break into and change the ledger. This makes it both public and secure.

But combined with another emerging (and much hyped) technology, quantum computing, blockchains seemingly immutable ledgers would be under threat.

Like blockchain, quantum computing has been making progress and headlines too.

The number of quantum computing companies and researchers continues to grow. And while there is a lot of focus on hardware, many are looking into the software as well.

Cryptography is a commonly debated topic because quantum computing poses a threat to traditional forms of computer security, most notably public key cryptography, which undergirds most online communications and most current blockchain technology.

But first, how does computer security work today?

Public key cryptography uses a pair of keys to encrypt information: a public key which can be shared widely and a private key known only to the keys owner. Anyone can encrypt a message using the intended receivers public key, but only the receiver can decrypt the message using her private key. The more difficult it is to determine a private key from its corresponding public key, the more secure the system.

The best public key cryptography systems link public and private keys using the factors of a number that is the product of two incredibly large prime numbers. To determine the private key from the public key alone, one would have to figure out the factors of this product of primes. Even if a classical computer tested a trillion keys a second, it would take up to 785 million times longer than the roughly 14 billion years the universe has existed so far due to the size of the prime numbers in question.

If processing power were to greatly increase, however, then it might become possible for an entity exercising such computing power to generate a private key from the corresponding public key. If actors could generate private keys from corresponding public keys, then even the strongest forms of traditional public key cryptography would be vulnerable.

This is where quantum computing comes in. Quantum computing relies on quantum physics and has more potential power than any traditional form of computing.

Quantum computing takes advantage of quantum bits or qubits that can exist in any superposition of values between 0 and 1 and can therefore process much more information than just 0 or 1, which is the limit of classical computing systems.

The capacity to compute using qubits renders quantum computers many orders of magnitude faster than classical computers. Google showed a D-Wave quantum annealing computer could be 100 million times faster than classical computers at certain specialized tasks. And Google and IBM are working on their own quantum computers.

Further, although there are but a handful of quantum computing algorithms, one of the most famous ones, Shors algorithm, allows for the quick factoring of large primes. Therefore, a working quantum computer could, in theory, break todays public key cryptography.

Quantum computers capable of speedy number factoring are not here yet. However, if quantum computing continues to progress, it will get there eventually. And when it does, this advance will pose an existential threat to public key cryptography, and the blockchain technology that relies on it, including Bitcoin, will be vulnerable to hacking.

So, is blockchain security therefore impossible in a post-quantum world? Will the advent of quantum computing render blockchain technology obsolete?

Maybe, but not if we can develop a solution first.

The NSA announced in 2015 that it was moving to implement quantum-resistant cryptographic systems. Cryptographers are working on quantum-resistant cryptography, and there are already blockchain projects implementing quantum-resistant cryptography. The Quantum Resistant Ledger team, for example, is working on building such a blockchain right now.

What makes quantum-resistant or post-quantum cryptography, quantum resistant? When private keys are generated from public keys in ways that are much more mathematically complex than traditional prime factorization.

The Quantum Resistant Ledger team is working to implement hash-based cryptography, a form of post-quantum cryptography. In hash-based cryptography, private keys are generated from public keys using complex hash-based cryptographic structures, rather than prime number factorization. The connection between the public and private key pair is therefore much more complex than in traditional public key cryptography and would be much less vulnerable to a quantum computer running Shors algorithm.

These post-quantum cryptographic schemes do not need to run on quantum computers. The Quantum Resistant Ledger is a blockchain project already working to implement post-quantum cryptography. It remains to be seen how successful the effort and others like it will prove when full-scale quantum computing becomes a practical reality.

To be clear, quantum computing threatens all computer security systems that rely on public key cryptography, not just blockchain. All security systems, including blockchain systems, need to consider post-quantum cryptography to maintain data security for their systems. But the easiest and most efficient route may be to replace traditional systems with blockchain systems that implement quantum-resistant cryptography.

Disclosure: The author owns assorted digital assets. The author is also a principal at Crypto Lotus LLC, a cryptocurrency hedge fund based out of the San Francisco Bay Area, and an advisor at Green Sands Equity, both of which have positions in various digital assets. All opinions in this post are the authors alone and not those of Singularity University, Crypto Lotus, or Green Sands Equity. This post is not an endorsement by Singularity University, Crypto Lotus, or Green Sands Equity of any asset, and you should be aware of the risk of loss before trading or holding any digital asset.

Image Credit: Morrowind /Shutterstock.com

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Is Quantum Computing an Existential Threat to Blockchain …