Daily Archives: August 6, 2017

UCLA researchers HongWen Jiang, professor of physics, and graduate student, Joshua Schoenfield have discovered a method for controlling and measuring the valley states of electrons in a silicon quantum dot, an essential key to stabilizing the qubits of a quantum computer. Their full findings are available in the journal Nature Communications.

A *quantum dot is a finite area of silicon that captures electrons, allowing researchers to alter their charge and spin. The valley state, a particular part of an electrons movement where it lays low in the texture of the silicones structure, has only recently been understood to have importance in the information storage of a qubit. If the silicon is imperfect in any way an electrons Valley state can be altered to dramatic and unpredictable effect. The valley state is inherent to the nature and action of a functioning qubit.

Normally, an electrons movement is quick and continual, challenging a researchers ability to keep it in a valley state for study. However, when UCLA scientists cooled a silicon quantum dot to almost absolute zero, the movement of electrons slowed enough for manipulation, measurement, and control. This was done by rapidly pulsing electricity to move individual electrons up and over the valleys.

Additionally, they were able to detect the fractional energy contrast between unique valleys, previously not possible by standard techniques.

Jiang and Schoenfield expect to further develop the technique used in order to have more control of qubits based on interacting valley states.

*Quantum dots(QD) are very smallsemiconductorparticles, only severalnanometresin size, so small that their optical and electronic properties differ from those of larger particles. They are a central theme innanotechnology. Source: Wikipedia

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New Methods of Controlling Electrons Could be Major in Quantum Computing - TrendinTech

July 31, 2017 by Fabio Bergamin Future quantum computers will be able to calculate the reaction mechanism of the enzyme nitrogenase. The image shows the active centre of the enzyme and a mathematical formula that is central for the calculation. Credit: Visualisations: ETH Zurich

Science and the IT industry have high hopes for quantum computing, but descriptions of possible applications tend to be vague. Researchers at ETH Zurich have now come up with a concrete example that demonstrates what quantum computers will actually be able to achieve in the future.

Specialists expect nothing less than a technological revolution from quantum computers, which they hope will soon allow them to solve problems that are currently too complex for classical supercomputers. Commonly discussed areas of application include data encryption and decryption, as well as special problems in the fields of physics, quantum chemistry and materials research.

But when it comes to concrete questions that only quantum computers can answer, experts have remained relatively vague. Researchers from ETH Zurich and Microsoft Research are now presenting a specific application for the first time in the scientific journal PNAS: evaluating a complex chemical reaction. Based on this example, the scientists show that quantum computers can indeed deliver scientifically relevant results.

A team of researchers led by ETH professors Markus Reiher and Matthias Troyer used simulations to demonstrate how a complex chemical reaction could be calculated with the help of a quantum computer. To accomplish this, the quantum computer must be of a "moderate size", says Matthias Troyer, who is Professor for Computational Physics at ETH Zurich and currently works for Microsoft. The mechanism of this reaction would be nearly impossible to assess with a classical supercomputer alone especially if the results are to be sufficiently precise.

One of the most complex enzymes

The researchers chose a particularly complex biochemical reaction as the example for their study: thanks to a special enzyme known as a nitrogenase, certain microorganisms are able to split atmospheric nitrogen molecules in order to create chemical compounds with single nitrogen atoms. It is still unknown how exactly the nitrogenase reaction works. "This is one of the greatest unsolved mysteries in chemistry," says Markus Reiher, Professor for Theoretical Chemistry at ETH Zurich.

Computers that are available today are able to calculate the behaviour of simple molecules quite precisely. However, this is nearly impossible for the nitrogenase enzyme and its active centre, which is simply too complex, explains Reiher.

In this context, complexity is a reflection of how many electrons interact with each other within the molecule over relatively long distances. The more electrons a researcher needs to take into account, the more sophisticated the computations. "Existing methods and classical supercomputers can be used to assess molecules with about 50 strongly interacting electrons at most," says Reiher. However, there is a significantly greater number of such electrons at the active centre of a nitrogenase enzyme. Because with classical computers the effort required to evaluate a molecule doubles with each additional electron, an unrealistic amount of computational power is needed.

Another computer architecture

As demonstrated by the ETH researchers, hypothetical quantum computers with just 100 to 200 quantum bits (qubits) will potentially be able to compute complex subproblems within a few days. The results of these computations could then be used to determine the reaction mechanism of nitrogenase step by step.

That quantum computers are capable of solving such challenging tasks at all is partially the result of the fact that they are structured differently to classical computers. Rather than requiring twice as many bits to assess each additional electron, quantum computers simply need one more qubit.

However, it remains to be seen when such "moderately large" quantum computers will be available. The currently existing experimental quantum computers use on the order of 20 rudimentary qubits respectively. It will take at least another five years, or more likely ten, before we have quantum computers with processors of more than 100 high quality qubits, estimates Reiher.

Mass production and networking

Researchers emphasise the fact that quantum computers cannot handle all tasks, so they will serve as a supplement to classical computers, rather than replacing them. "The future will be shaped by the interplay between classical computers and quantum computers," says Troyer.

With regard to the nitrogenase reaction, quantum computers will be able to calculate how the electrons are distributed within a specific molecular structure. However, classical computers will still need to tell quantum computers which structures are of particular interest and should therefore be calculated. "Quantum computers need to be thought of more like a co-processor capable of taking over particular tasks from classical computers, thus allowing them to become more efficient," says Reiher.

Explaining the mechanism of the nitrogenase reaction will also require more than just information about the electron distribution in a single molecular structure; indeed, this distribution needs to be determined in thousands of structures. Each computation takes several days. "In order for quantum computers to be of use in solving these kinds of problems, they will first need to be mass produced, thereby allowing computations to take place on multiple computers at the same time," says Troyer.

Explore further: Developing quantum algorithms for optimization problems

More information: Markus Reiher et al. Elucidating reaction mechanisms on quantum computers, Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1619152114

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Clarifiying complex chemical processes with quantum computers - Phys.Org

In BriefQuantum computers are rapidly developing, but when will we beable to add one to our Christmas lists? Here is a timeline for whenyou can expect to see quantum computers on the shelves of yourlocal tech store. Technological Revolution

Quantum computers are making an entrance, and its a dramatic one. Even in its infancy, the technology isoutperforming the conventional competition and is expected to make the field of cryptography as we know it obsolete. Quantum computing has the potential to revolutionize several sectors, including the financial and medical industries.

Quantum computers can processesa greater number of calculations because they rely on quantum bits(qubits), which canbe onesand zeroessimultaneously, unlikeclassical bits that must be either a one or a zero. The company D-Wave is releasing a version of a quantum computer this year, but its not a fully formed embodiment of this technology. So we asked our readers when we should expect to see quantum computers available as consumer products?

Almost 80 percent of respondents believed we will be able to buy our own quantum computer before 2050, and the decade that received the most votes about 34 percent was the 2030s. Respondent Solomon Duffin explained why his prediction, the2040s, was slightly more pessimistic than those of the majority.

In the 2020s, we will have quantum computers that are significantly better than super computers today, but they most likely wont be in mass use by governments and companies until the 2030s. Eventually toward the end of the 2030s and early 2040s theyll shrink down to a size and cost viable for consumer use. Before that point even with the exponential growth of technology I dont think that it would be cost efficient enough for the average consumer to replace regular computing with quantum computing.

Quantum computers are indeed currently out of the price range of the average consumer, and will likely stay that way for a few years at least. The $15 million price tag for theD-Wave 2000Qhas a long way to drop before it makes it to a Black Friday sale.

But the technology is rapidly advancing, and experts are optimistic that we will soon see a bonafide, functioning quantum computer in all of its glory. In fact, an international team of researchers wrote in a study published in Physical Review, Recent improvements in the control of quantum systems make it seem feasible to finally build a quantum computer within a decade.

Andrew Dzurak,Professor in Nanoelectronics at University of New South Wales, said in an interview with CIOthat he hopes quantum computers will be able to advance scientific research, for example, by simulating what potential drugs would do in the human body. However,Dzurak said he expects it will take 20 years for quantum computers to be useful enough for that kind of application.

I think that within ten years, there will be demonstrations of modelling of certain chemicals and drugs that couldnt be done today but I dont think there will be a convenient, routine [system] that [people] can use, Dzurak said in the interview. To move to that stage will take another decade further beyond that.

Dzurak also expressed his doubts that quantum computers will be very useful to the average consumer since they can get most of what they want using conventional computers. But D-Wave international president Bo Ewald thinks thats just because we havent imagined what we could do with the technology yet. This is why D-Wave has released a new software toolto help developers make programs for the companys computers.

D-Wave is driving the hardware forward, Ewald said in an interview with Wired. But we need more smart people thinking about applications, and another set thinking about software tools.

See all of the Futurism predictions and make your own predictions here.

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When Will Quantum Computers Be Consumer Products? - Futurism

Computing power is reaching a crisis point. If we continue to follow a trend in place since computers were introduced, by 2040 we will not have the capability to power all of the machines in the world. Unless we can crack quantum computing.

Quantum computers promise faster speeds and stronger security than their classical counterpart and scientists have been striving to create a quantum computer for decades. But what is quantum computing and why have we not achieved it yet?

Quantum computing differs to classical computing in one fundamental way the way information is stored. Quantum computing makes the most of a strange property of quantum mechanics, called superposition. It means one unit can hold much more information than the equivalent in classical computing.

In computing, information is stored in bits in either the state 1 or 0, like a light switch either turned on or off. By contrast, in quantum computing the unit of information can be 1 or 0, or a superposition of the two states.

Think of it like a sphere, with a 1 written at the north pole and a 0 at the south. A classical bit can be found at either pole, but a quantum bit, or qubit, could be found on any point on the surface of the sphere.

Quantum bits that can be on and off at the same time, provide a revolutionary high-performance paradigm where information is stored and processed more efficiently," Dr Kuei-Lin Chiu, who researches quantum mechanical behaviour of materials at the Massachusetts Institute of Technology, told Alphr.

The ability to store a much greater amount of information in one unit means quantum computing has the potential to be faster and more energy efficient than computers we use today. So why is it so hard to achieve?

Qubits, the backbone of a quantum computer, are tricky to make and, once made, are even harder to control; scientists must get them to interact in specific ways that would work in a quantum computer.

Researchers have tried using superconducting materials, ions held in ion traps or individual neutral atoms, as well as molecules of varying complexity to build them. But, making them hold onto quantum information for a long time is proving difficult.

In recent research, scientists at MIT devised a new approach, using a cluster of simple molecules made of just two atoms as qubits.

We are using ultracold molecules as qubits Professor Martin Zwierlein, lead author of the paper told Alphr. Molecules have long been proposed as a carrier of quantum information, with very advantageous properties over other systems like atoms, ions, superconducting qubits etc.

Here we show for the first time that you can store such quantum information for extended periods of time in a gas of ultracold molecules. Of course, an eventual quantum computer will have to also make calculations, i.e. have the qubits interact with each other to realise so-called gates. But first, you need to show that you can even hold on to quantum information, and thats what we have done.

The qubits created were found to be capable of holding onto the quantum information for longer than previous attempts, but still only for one second. This might sound short, but it is "in fact on the order of a thousand times longer than a comparable experiment that has been done" explained Zwierlein.

It is not just qubits, however. Scientists also need to work out what to make the quantum computing chips out of.

Chius paper, published earlier this year, found ultra-thin layers of materials could form the basis for a quantum computing chip. The interesting thing about this research is how we choose the right material, find out its unique properties and use its advantage to build a suitable qubit, Chiu, told Alphr.

Moores Law predicts that the density of transistors on silicon chips doubleapproximately every 18 months, Chiu told Alphr. However, these progressively shrunken transistors will eventually reach a small scale where quantum mechanics play an important role.

Moores Law, which Chiu referred to, is a computing term developed by Intel co-founder Gordon Moore in 1970. It states that the overall processing power for computers doubles about every two years. As Chiu states, the density of the chips decreases a problem that quantum computing chips can potentially answer.

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What is quantum computing and why does the future of Earth depend on it? - Alphr

They picked a knotty problem understanding how the enzyme nitrogenase allows plants to use nitrogen from the atmosphere to make their own fertilizer something that is unknown.

Computers available today, said EHT chemistry professor Markus Reiher can calculate the behaviour of simple molecules quite precisely, but not nitrogenase , which is too complex.

Existing methods and classical supercomputers can be used to assess molecules with about 50 strongly interacting electrons at most, he said, but there are significantly more at the active centre of nitrogenase enzyme, and classical computing effort doubles with each additional electron.

A hypothetical quantum computer with 100 to 200qubits was imagined, that could compute electron positions for a particular arrangement of atoms in a few days, and the results of many of these calculations could be combined to determine the nitrogenase reaction step by step.

That quantum computers are capable of solving such challenges is partially their different structure compared to classical computers. According to ETH, a quantum computers needs only one extra qubit per added electron, rather than a doubling if bits.

Our resource estimates show that, even when taking into account the substantial overhead of quantum error correction, and the need to compile into discrete gate sets, the necessary computations can be performed in reasonable time on small quantum computers, said the research team in Elucidating reaction mechanisms on quantum computers, published in the proceedings of the US National Academy of Sciences.

When will such moderately large quantum computers will be available?

Current experimental quantum computers use ~20 rudimentary qubits, said Reiher, estimating that it will take at least another five years, or more likely ten, before quantum computers more than 100 high quality qubits exist.

The researchers emphasise that quantum computers cannot handle all tasks: they will supplement classical computers. The future will be shaped by the interplay between classical computers and quantum computers, said ETH computatonal physicist Professor Matthias Troyer

For nitrogenase, according to ETH, suchcomputers will be able to calculate how the electrons are distributed within a specific molecular structure. But classical computers will be required to tell the quantum computer which potential structures are of particular interest and should be calculated.

Quantum computers need to be thought of more like a co-processor capable of taking over particular tasks from classical computers, thus allowing them to become more efficient, said Reiher.

In order for quantum computers to be of use in solving these kinds of problems, they will first need to be mass produced, thereby allowing computations to take place on multiple computers at the same time, said Troyer.

Continue reading here:

Exactly what could quantum computers do? - Electronics Weekly