Category Archives: Quantum Computing

Graphene, the wonder-material which is the atom-thick two-dimensional form of carbon, is once again showing its potential use in the development of quantum computers. Researchers from cole Polytechnique Fdrale de Lausanne (EPFL) in Switzerland demonstrated a graphene-based quantum capacitor, which can produce stable qubits the quantum counterpart of digital bits used in regular computers.

While a digital bit works on a binary system and can store data as either 0 or 1, quantum bits or qubits can exist in two states simultaneously and also exhibit arbitrary superposition, which greatly increases their storage and computing power, by several orders of magnitude. However, creating them requires very controlled conditions, such as extremely low temperatures.

Read: Artificial Atom In Graphene Has Potential Quantum Computing Applications

The capacitor designed by the EPFL researchers consists of boron nitride an insulating material resistant to heat and chemicals placed between two sheets of graphene. Due to the sandwich structure and the unusual properties of graphene, a nonlinear charge is generated, which is necessary to creation of qubits.

A nonlinear charge refers to the fact that the incoming charge introduced to the capacitor is not proportional to the voltageproduced.

The design developed by EPFL is relatively easier to fabricate than many other known cryogenic quantum devices, according to a statement by the researchers, but still needs low temperatures to work. It has very low sensitivity to electrical interference, which is a good thing, is not as bulky as some of the other similar devices and also avoids physical mechanical motion as the structure is not suspended.

Creating qubits is not all the device is good for. It could significantly improve the way quantum information is processed but there are also other potential applications too. It could be used to create very nonlinear high-frequency circuits all the way up to the terahertz regime or for mixers, amplifiers, and ultra strong coupling between photons, according to the statement.

This is an insulating boron nitride sandwiched between two graphene sheets. Photo: EPFL/ LPQM

The structure of the graphene-based capacitor for generating qubits has been described in detail in an open-access paper published Thursday in the journal npj 2D Materials and Applications, under the title Nonlinear graphene quantum capacitors for electro-optics.

Generating stable qubits is one of the biggest challenges to the development of functional and scalable quantum computers. Other than graphene, researchers have been trying various other methods to create qubits, including techniques that use light and lasers, silicon-based nanostructures, and even diamonds.

There is also an ongoing debate about which of the two approaches to quantum computing superconducting or trapped ions is better to achieve stable qubits and scalable circuits. While most researchers in the field are taking the superconducting route, a reprogrammable quantum device the first of its kind was created a few months ago using trapped ions.

Traditional computer manufacturing companies, not wanting to be left behind when the future arrives, have also jumped onto the quantum bandwagon. In November 2016, Microsoft announced it was ready to move from research to engineering.

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Quantum Computing Could Use Graphene To Create Stable Qubits - International Business Times

Enlarge / IBM's new 16-qubit quantum computer.

The race to build the first useful quantum computer continues apace. And, like all races, there are decisions to be made, including the technology each competitor mustchoose. But, in science, no one knows the race course, where the finish line is, or even if the race has any sort of prize (financial or intellectual) along the way.

On the other hand, the competitors can take a hand in the outcome by choosing the criteria by which success is judged. And, in this rather cynical spirit, we come to IBM's introduction (PDF) of "quantum volume" as a single numerical benchmark for quantum computers. In the world of quantum computing, it seems that everyone is choosing their own benchmark. But, on closer inspection, the idea of quantum volume has merit.

Many researchers benchmark using gate speedhow fast a quantum gate can perform an operationor gate fidelity, which is how reliable a gate operation is. But these single-dimensional characteristics do not really capture the full performance of a quantum processor. For analogy, it would be like comparing CPUs by clock speed or cache size, but ignoring any of the other bazillion features that impact computational performance.

The uselessness of these various individual comparisons were highlighted when researchers compared a slow, but high-fidelity quantum computer to a fast, but low-fidelity quantum computer, and came to the conclusion that the result was pretty much a draw.

It gets even worse when you consider that, unlike classical computers, you need a certain number of qubits to even carry out a calculation of a certain computational size. So, maybe, IBM researchers thought, a benchmark needs to somehow encompass the idea of what a quantum computer is capable of calculating, but not necessarily how fast it will perform a calculation.

The IBM staff are building on a concept called circuit depth. Circuit depth starts with the idea that, because quantum gates can always introduce an error, there is a maximum number of operations that can be performed before it is unreasonable to expect the qubit state to be correct. Circuit depth is that number, multiplied by the number of qubits. If used honestly, this provides a reasonable idea of what a quantum computer can do.

The problem with depth is that you can keep the total number of qubits constant (and small), while reducing the error rate to very close to zero. That gives you a huge depth, but, only computations that fit within the number of qubits can be calculated. A two-qubit quantum computer with enormous depth is still useless.

Thegoal, then, is to express computational capability, which must include the number of qubits and the circuit depth. Given an algorithm and problem size, there is a minimum number of qubits required to perform the computation. And, depending on how the qubits are connected to each other, a certain number of operations have to be performed to carry out the algorithm. The researchers express this by comparing the maximum number of qubits involved in a computation to the circuit depth and take the square of the smaller number. So, the maximum possible quantum volume is just the number of qubits squared.

To give you an idea, a 30-qubit system with no gate errors has a quantum volume of 900 (no units for this). To achieve the same quantum volume with imperfect gates, the error rate has to be below 0.1 percent. But, once this is achieved, all computations require 30 or fewerqubits can be performed on that quantum computer.

That seems simple enough, but figuring out the depth takes a bit of work because it depends on how the qubits are interconnected. So, the benchmark indirectly takes into account architecture.

The idea is that the minimum number of operations required to complete an algorithm occurs when every qubit is directly connected to every other qubit. But, in most cases, direct connections like that arenot possible, so additional gates or qubits have to be added to connect qubits that are distant from each other. But each gate operation comes with the chance of introducing an error, so the depth changes.

The researchers calculated the error rate that would be required to obtain a certain quantum volume. The idea is that many computations can be broken up into a series of two-qubit computations. Then, for a given qubit arrangement (the connections between qubits), you can figure out how many operations it takes to perform a two-qubit operation between every qubit. From that you can figure out the required depth, and the minimum error rate.

And, actually, the results are not too badif you like to make fully interconnected qubit systems. Then you end up with error rates that, depending on the number of qubits, are around 1 per 1,000. But, the penalty for reduced interconnections is severe, with circuits like the latest IBM processor requiring at least a factor of ten better error rates than a fully connected quantum computer. That is if you believe the calculation. Unfortunately, if you compare the calculated error rate, the number of qubits and the quantum volume, the results are inconsistent. We've reached out to IBM and will update when they respond. Unfortunately, when you read the scale wrong, you get inconsistent results. Once you correct for reader error, it all works out fine.

To put it in perspective, gate fidelities in IBM's 5 qubit quantum computer are, at best, 99 percent. So, one operation per 100 goes wrong. And that quantum computer is not fully interconnected. And, indeed, if you perform the calculation, the quantum volume is 25, which requires an error rate on the order of one percent, which approximately agrees with the observed capabilities. If IBM's newly announced 17-qubit quantum computer has the same gate fidelity, then it will have a quantum volume of 35, a small increase on the five-qubit system. To get anywhere near the maximum of 290, the IBM crew will have to increase the gate fidelity to about 99.7 percent, which would be a significant technological achievement.

And, this is where the new benchmark comes in very handy. It gives researchers a very quick way to estimate technology requirements. With some rather simple follow-up calculations the advantages and disadvantages of different architectural choices can be quickly evaluated. I can imagine quantum volume finding quite widespread use.

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Bigger is better: Quantum volume expresses computer's limit - Ars Technica

While everyones in a rush to get to the end of the quantum computer race, has anyone really given a moment thought as to who will actually program these machines? The idea of achieving quantum supremacy came after Google unveiled its new quantum chip design and is all about creating a device that can perform calculation impossible for a conventional computer to carry out.

Quantum computers should have no trouble in outperforming conventional computers as they work on the basis of qubits. Unlike bits that run conventional computers and either a 0 or a 1, qubits can be both at the same time. This is a phenomenon known as superposition. But in order to demonstrate that thousands of qubits would be needed, and right now, thats just not possible. So instead of Google is planning to compare the computers ability to simulate the behavior of a random arrangement of quantum circuits and estimate it will take around 50 qubits to outdo the most powerful of computers.

IBM is getting ready to release the worlds first commercial universe quantum computing service later this year that will give users the chance to connect to one of its quantum computers via the cloud for a fee. But, there are still many hurdles to overcome before this technology becomes mainstream. One of these problems is that programming a quantum computer is much harder than programming a conventional computer. So, whos going to program them?

There are a number of quantum simulators available now that will help users get familiar with quantum computing, but its not the real thing and is likely to behave very differently. MIT physicist, Isaac Chuang, said, The real challenge is whether you can make your algorithm work on real hardware that has imperfections. It will take time for any computer programmer to learn the skills needed for quantum computing, but until the systems have been developed, what will they learn on?

This is one of the reasons for the push in making quantum devices more accessible. D-wave made available their Qbsoly and Qmasm tools earlier this year in an attempt to get more people into the realms of quantum computing. If the tools are available, more people will be tempted to have a go and budding quantum computer scientists will be born. And as Googles researchers wrote in a statement, If early quantum-computing devices can offer even a modest increase in computing speed or power, early adopters will reap the rewards.

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Quantum Computers Sound Great, But Who's Going to Program Them? - TrendinTech

BURNABY, BC--(Marketwired - May 16, 2017) - D-Wave Systems Inc., the leader in quantum computing systems and software, today announced that it has received new capital in the form of convertible notes from the Public Sector Pension Investment Board ("PSP Investments"). PSP Investments funded US$30 million at closing, with an additional US$20 million available at D-Wave's option upon the achievement of certain milestones. This facility brings D-Wave's total funding to approximately US$200 million. The new capital is expected to enable D-Wave to deploy its next-generation quantum computing system with more densely-connected qubits, as well as platforms and products for machine learning applications.

"This commitment from PSP Investments is a strong validation of D-Wave's leadership in quantum computing," said Vern Brownell, CEO of D-Wave. "While other organizations are researching quantum computing and building small prototypes in the lab, the support of our customers and investors enables us to deliver quantum computing technology for real-world applications today. In fact, we've already demonstrated practical uses of quantum computing with innovative companies like Volkswagen. This new investment provides a solid base as we build the next generation of our technology."

This latest funding comes on the heels of significant momentum for D-Wave. Milestones achieved so far in 2017 include:

About D-Wave Systems Inc. D-Wave is the leader in the development and delivery of quantum computing systems and software, and the world's only commercial supplier of quantum computers. Our mission is to unlock the power of quantum computing for the world. We believe that quantum computing will enable solutions to the most challenging national defense, scientific, technical, and commercial problems. D-Wave's systems are being used by some of the world's most advanced organizations, including Lockheed Martin, Google, NASA Ames, USRA, USC, Los Alamos National Laboratory, and Temporal Defense Systems. With headquarters near Vancouver, Canada, D-Wave's U.S. operations are based in Palo Alto, CA and Hanover, MD. D-Wave has a blue-chip investor base including PSP Investments, Goldman Sachs, Bezos Expeditions, DFJ, In-Q-Tel, BDC Capital, Growthworks, 180 Degree Capital Corp., International Investment and Underwriting, and Kensington Partners Limited. For more information, visit: http://www.dwavesys.com.

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D-Wave Closes $50M Facility to Fund Next Generation of Quantum Computers - Marketwired (press release)

Centimetre-sized chip with nanoscale refrigeration. Credit: Kuan Yen Tan

Quantum computers have been hailed as the computers of the future because of their potential to solve the most complex of problems within a reasonable time frame. What differentiates a quantum computer from a traditional electronic computer is its use of quantum bits (qubits for short) instead of regular bits. A bit can only represent one of two states, either 0 or 1. In contrast, a qubit can represent more than one state 0, or 1, or both 0 and 1. And this is made possible through the quantum quirks known as superpositioning and entanglement. It is this bizarre ability to be in two states at once that makes a quantum computers computational power exceptional, extraordinary and virtually elusive up to now.

In spite of their differences in terms of functioning capabilities, one thing that a conventional computer and a quantum computer have in common is the need to keep both cool enough so their components do not overheat and malfunction or shut down completely. Traditional computers have their cooling fans. For quantum computers, its not as simple.

For starters, qubits must be protected from any kind of external disturbance because a slight interference will mess up the superpositioning state, resulting in errors and negating what a qubit is supposed to be for in the first place. Also, because qubits heat up while performing calculations, theres a need to reset them to their low temperature state or ground state before the next round of calculations can be done. For a quantum computer to be useful at all, it needs a cooling mechanism that can do this job (referred to as initializing) quickly.

This is where the work of Mikko Mttnen and his colleagues comes in. They are claiming that they have built a cooling device specifically designed for a quantum circuit that is capable of quickly initializing quantum devices, thus minimizing the incidence of errors when doing quantum computing.

The nanoscale refrigerator the team invented involves the use of voltage-controllable electron tunnelling to cool a qubit-like superconducting resonator through a two-nanometer-thick insulator. To make it work, current from an external voltage source is applied to electrons, giving them an amount of energy insufficient for direct tunnelling. This forces the electrons to capture the remaining amount of energy needed for tunnelling from the nearby quantum device, thus making the quantum device lose energy and cool down.

To turn off cooling, the external voltage simply needs to be adjusted to zero. In that condition, the electrons wont have enough energy (even if they capture energy from the quantum device) to move through the insulator.

As Mikko Mttnen aptly describes it their refrigerator keeps quanta in order.

Going forward, the team is planning to cool actual qubits, instead of just resonators. They will also work on lowering the minimum achievable temperature and speeding up the on/off switch.

The research was recently published in the journal Nature Communications.

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Scientists Invent Nanoscale Refrigerator For Quantum Computers - Wall Street Pit

Researchers in Professor of Engineering Jelena Vuckovics lab are pursuing smaller, faster computers with work in the cutting-edgefield of quantum computing.

Most currentcomputing is based on a binary system of ones and zeros generated by electricity. Instead of using electricity and digits, quantum computing analyzes particles of light called quanta, emitted by lasers striking single electrons. The light particles indicate the way each electron is spinning; they allow transmission of more complicated information than would be possible with just binary numbers.

That greater range of possibilities forms the basis for more complex computing, Marina Radulaski, a postdoctoral fellow in Vuckovics lab, toldStanford News.

According to Vuckovic, whose research is at theforefront of quantum computing, the technology is applicable to a wide variety of problems involving many variables for example, issues in fields like cryptography and data mining.

When people talk about finding a needle in a haystack, thats where quantum computing comes in, Vuckovic said.

For the last two decades, Vuckovic has sought to develop new kinds of quantum computer chips. Recently, she has joined forces with others around the globe to test out three different ways of isolating electronsfor interaction with lasers.

Each of the three strategies leverages semiconductor crystals, a material whose lattice of atoms can be modified subtly to hold electrons.

Many companies tackling quantum computing seek to cool materials almost to absolute zero, the temperature at which atoms stop moving. But one of the materials Vuckovic and her colleagues have been exploring could function at standard room temperatures. This normal-temperature optioncould help quantum computing become more widespread.

To fully realize the promise of quantum computing we will have to develop technologies that can operate in normal environments, Vuckovic said. The materials we are exploring bring us closer toward finding tomorrows quantum processor.

We dont know yet which approach is best, so we continue to experiment, she added.

Contact Hannah Knowles at hknowles at stanford.edu.

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Researchers seek to advance quantum computing - The Stanford Daily

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In a world where we are relying increasingly on computing, to share our information and store our most precious data, the idea of living without computers might baffle most people.

But if we continue to follow the trend that has been in place since computers were introduced, by 2040 we will not have the capability to power all of the machines around the globe, according to a recent report by the Semiconductor Industry Association.

To prevent this, the industry is focused on finding ways to make computing more energy efficient, but classical computers are limited by the minimum amount of energy it takes them to perform one operation.

This energy limit is named after IBM Research Lab's Rolf Landauer, who in 1961 found that in any computer, each single bit operation must use an absolute minimum amount of energy. Landauer's formula calculated the lowest limit of energy required for a computer operation, and in March this year researchers demonstrated it could be possible to make a chip that operates with this lowest energy.

It was called a "breakthrough for energy-efficient computing" and could cut the amount of energy used in computers by a factor of one million. However, it will take a long time before we see the technology used in our laptops; and even when it is, the energy will still be above the Landauer limit.

This is why, in the long term, people are turning to radically different ways of computing, such as quantum computing, to find ways to cut energy use.

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.

"Traditionally qubits are treated as separated physical objects with two possible distinguishable states, 0 and 1," Alexey Fedorov, physicist at the Moscow Institute of Physics and Technology told WIRED.

"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'."

D-Wave

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.

Last year, a team of Google and Nasa scientists found a D-wave quantum computer was 100 million times faster than a conventional computer. But moving quantum computing to an industrial scale is difficult.

IBM recently announced its Q division is developing quantum computers that can be sold commercially within the coming years. Commercial quantum computer systems "with ~50 qubits" will be created "in the next few years," IBM claims. While researchers at Google, in Nature comment piece, say companies could start to make returns on elements of quantum computer technology within the next five years.

Computations occur when qubits interact with each other, therefore for a computer to function it needs to have many qubits. The main reason why quantum computers are so hard to manufacture is that scientists still have not found a simple way to control complex systems of qubits.

Now, scientists from Moscow Institute of Physics and Technology and Russian Quantum Centre are looking into an alternative way of quantum computing. Not content with single qubits, the researchers decided to tackle the problem of quantum computing another way.

"In our approach, we observed that physical nature allows us to employ quantum objects with several distinguishable states for quantum computation," Fedorov, one of the authors of the study, told WIRED.

The team created qubits with various different energy "levels", that they have named qudits. The "d" stands for the number of different energy levels the qudit can take. The term "level" comes from the fact that typically each logic state of a qubit corresponds to the state with a certain value of energy - and these values of possible energies are called levels.

"In some sense, we can say that one qudit, quantum object with d possible states, may consist of several 'virtual' qubits, and operating qudit corresponds to manipulation with the 'virtual' qubits including their interaction," continued Federov.

"From the viewpoint of abstract quantum information theory everything remains the same but in concrete physical implementation many-level system represent potentially useful resource."

Quantum computers are already in use, in the sense that logic gates have been made using two qubits, but getting quantum computers to work on an industrial scale is the problem.

"The progress in that field is rather rapid but no one can promise when we come to wide use of quantum computation," Fedorov told WIRED.

Elsewhere, in a step towards quantum computing, researchers have guided electrons through semiconductors using incredibly short pulses of light. Inside the weird world of quantum computers

These extremely short, configurable pulses of light could lead to computers that operate 100,000 times faster than they do today. Researchers, including engineers at the University of Michigan, can now control peaks within laser pulses of just a few femtoseconds (one quadrillionth of a second) long. The result is a step towards "lightwave electronics" which could eventually lead to a breakthrough in quantum computing.

A bizarre discovery recently revealed that cold helium atoms in lab conditions on Earth abide by the same law of entropy that governs the behaviour of black holes. What are black holes? WIRED explains

The law, first developed by Professor Stephen Hawking and Jacob Bekenstein in the 1970s, describes how the entropy, or the amount of disorder, increases in a black hole when matter falls into it. It now seems this behaviour appears at both the huge scales of outer space and at the tiny scale of atoms, specifically those that make up superfluid helium.

"It's called an entanglement area law, explained Adrian Del Maestro, physicist at the University of Vermont. "It points to a deeper understanding of reality and could be a significant step toward a long-sought quantum theory of gravity and new advances in quantum computing.

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quantum computing - WIRED UK

The race on quantum technologies is on in a big way. Weve already seen big investments coming from both China and the United States, and now Europe is jumping in on the action too. Last year the European Commission announced its plans to invest 1 billion Euros ($1.1 billion) into quantum mechanic research. However, experts are concerned that partners are reluctant to invest.

A meeting was held by an advisory group steering the Quantum Technology Flagship project on 7 April at the Russian Centre of Science and Culture in London. Here the group gave details of how the project will work which includes exploiting the behavior shown by quantum systems in order to develop new technologies such as ultra-accurate sensors and super-secure communication systems. But is it too little too late? Various other countries are already developing these technologies, including China and the U.S.

Europe cannot afford to miss this train, says Vladmir Buzek, a member of the steering group and physicist at the Research Center for Quantum Information of the Slovak Academy of Sciences in Bratislava. The industry here is really waiting too long. Launched just last year, this quantum project is a decade-long initiative that will work differently to previous efforts, operating with open calls throughout to ensure flexibility in funding the best researchers. The focus of the European Flagship will be on four distinct areas of quantum technologies: communication, sensing, computing, and simulation.

China is clearly in the lead currently when it comes to quantum communication. They hold the most patents globally in this field with the United States leading to patents involving quantum computers and ultrasensitive sensors. One of the big problems Europe face is the loss of the United Kingdom following the Brexit vote. The project is due to kick off the same year as the United Kingdom are due to exit the European Union (2019). But experts suggest the timing may actually be a good thing and are hopeful the United Kingdom can still participate in some form.

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Home News Computer Europe Takes Quantum Computing to the Next Level With this Billion Euro... - TrendinTech

In a Nature Communications publication, the results of the collaboration between scientists of the Institut Laue-Langevin (ILL), the University of Parma, ISIS and the University of Manchester, the (Cr7Ni)2 dimer has been used as a benchmark system to demonstrate the capability of four-dimensional inelastic neutron scattering to investigate entanglement between molecular qubits. By utilising high-quality single crystals and the full capabilities of the time-of-flight spectrometer IN5, the team was able to demonstrate and quantify the entanglement through the huge amount of data they were able to extract from the 4D phase space (Qx,Qy,Qz,E), where Q is the momentum-transfer vector and E the energy transfer. Indeed, the neutron cross-section directly reflects dynamical correlations between individual atomic spins in the molecule. Hence, the corresponding pattern of maxima and minima in the measured neutron scattering intensity as a function of Q is a sort of portrayal of the entanglement between the molecular qubits. Furthermore, the team has also developed a method to quantify entanglement from INS data.

Such a measurement opens up remarkable perspectives in understanding entanglement in complex spin systems. The research on molecular nanomagnets has been an attractive topic on the IN5 time-of-flight spectrometer since many years. In this recent work the top class chemistry and theoretical work meet the advanced neutron scattering methods to highlight the intricate physics of quantum entanglement, guiding further research towards a better understanding of the practical challenges in quantum information technology, said Dr Hannu Mutka and Dr Jacques Ollivier, ILL scientists.

With this benchmark measurement it looks as though neutrons will continue to be an essential tool in helping molecular nanomagnets realise their potential for quantum technologies of the future.

Nextbigfuture interviewed the researchers.

1. What are the next steps in this research? By exploiting the (Cr7Ni)2 supramolecular dimer as a benchmark, we have shown that the four-dimensional inelastic neutron scattering technique (4D-INS) enables one to portray and quantify entanglement between weakly coupled molecular nanomagnets, which provide ideal test beds for investigating entanglement in spin systems. The next steps will be the application of 4D-INS to dimers of more complex molecular qubits, like those containing 4f or 5f magnetic ions or to supramolecular compounds with more than two qubits. 2. Can the timing be seen for possible commercialization? The use of molecular nanomagnets for quantum information processing (QIP) is a relatively unexplored field. Therefore, as in other approaches to implement qubits, commercialisation is certainly not immediate. However, molecular magnetism constitutes an alternative route to QIP that uses low-cost, yet powerful, chemical methods to fabricate basic components and integrate them in future devices. 3. Is there an effort to enable qubits via this approach? Neutron scattering is a very powerful technique and enables one to achieve a sound characterisation of both molecular qubits and their supramolecular assemblies. Therefore, we plan to apply it to new interesting systems in the near future. In addition, we believe that our work will stimulate similar studies by other research groups. In this way, promising molecules with improved characteristics for QIP will be identified. 4. How does this work fit into a larger area of research? I.e. broad advances are happening and this is just a part. This work provides an important tool for molecular qubits, which in turn fit the broad quest for quantum information technologies. The latter constitutes one of the most important current research areas. Indeed, some of the most important private companies and international institutions are investing a huge amount of money on this subject. For instance, the European Commission will launch a 1 billion quantum technologies flagship in 2018. 5. What do the researchers see as highlights for how this work advances the state of the art?

Experimentally measuring entanglement in complex systems is generally very difficult. In this work, we have put forward a method to demonstrate and quantify entanglement between molecular qubits, by measuring the dependence of the neutron cross-section on the three components of the momentum transfer Q. Such measurements are challenging, but we have demonstrated this with the spectrometer IN5 at the Institut Laue-Langevin, indicating that they can now be performed exploiting state-of-the-art neutron spectrometers.

6. Do the researchers have a context or vision they can share? Quantum computers will be powerful devices able to solve problems that are impossible even on the best traditional computers. Molecular nanomagnets might provide a relatively cheap route to reach this extremely ambitious goal and 4D-INS can be an important tool in the understanding and engineering of molecules with the right characteristics for efficiently encoding and processing quantum information. 7. Anything else that the researchers think is relevant in understanding this work and its importance? In our opinion, this work represents a very good example of how the interplay between theory, experiments and chemical synthesis can be very fruitful and can enable us to make a significant step toward an ambitious objective.

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Molecular magnets closer to application in quantum computing - Next Big Future

A team of researchers from Stanford University has been investigating some new materials that they believe will bring us closer to building practical quantum computers.

One possible way to build quantum computers would be to use lasers to isolate spinning electrons inside a semiconductor material. When the laser hits the electron, it shows how the electron is spinning by emitting one or more light particles. The spin states can then be used as the most fundamental building blocks for quantum computing, the same way conventional computing uses 1s and 0s.

According to Stanford electrical engineering Professor Jelena Vuckovic, who has been investigating these new materials to build quantum computers, quantum computing would be ideal for studying biological systems, doing cryptography, or data mining, as well as for any other complex problem that cant be solved by conventional computers.

When people talk about finding a needle in a haystack, thats where quantum computing comes in, said Vuckovic.

The challenge in isolating spinning electrons is finding a material that can confine the electrons when the lasers hit them. Vuckovics team has identified three materials that can potentially do this: quantum dots, diamonds, and silicon carbide.

A quantum dot is a small amount of indium arsenide inside a crystal of gallium arsenide. The atomic properties of the two materials are known to trap spinning electrons.

In a recent paper, Kevin Fischer, a graduate student in the Vuckovic lab, described how the laser-electron processes can be used within a quantum dot system to control the input and output of light. For instance, by applying more power behind the lasers, two photons could be emitted instead of one. This could be used as an alternative to the 1s and 0s of conventional computers.

One issue is that the quantum dot system still requires cryogenic cooling, which doesnt make it a suitable candidate for general-purpose computing.

Vuckovics team has also been investigating modifying the crystalline lattice of a diamond to trap light in what is known as a color center. The team replaced some of the carbon atoms in the diamonds crystalline lattice with silicon atoms.

Like the quantum dots approach, doing quantum computing within diamond color centers requires cryogenic cooling.

Silicon carbide is a hard and transparent crystal that is used to make clutch plates, brake pads, and bulletproof vests, among other things. Prior research has shown that silicon carbide could be modified to create color centers at room temperature, but not in a way thats efficient enough to create a quantum chip.

Vuckovics team was able to eliminate some of the atoms in the silicon carbide lattice to create much more efficient color centers. The team also fabricated nanowires around the color centers to improve photon extraction.

Trapping electrons at room temperature could be a significant step forward for quantum computers, according to Vuckovich. However, she and her team are also not sure which method to create a practical quantum computer will work best in the end.

Some of the biggest technology companies in the world are working on building quantum computers right now, including Google, IBM, and Microsoft. Teams at many universities around the world are also experimenting with different approaches to building quantum computers.

Both Google and IBM believe well reach quantum supremacy--the point when quantum computers will be faster than conventional computers at solving a certain type of complex problems--when quantum computers have around 50 qubits (from the fewer than 10 qubits they do now). The two companies expect this goal to be reached in the next few years.

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New Materials Could Make Quantum Computers More Practical - Tom's Hardware