Category Archives: Quantum Computing

Stanford University electrical engineering Professor Jelena Vuckovic and colleagues at her laboratory are working on new materials that could become the basis for quantum computing.

While silicon transistors in traditional computers push electricity through devices to create digital ones and zeros, quantum computers work by isolating spinning electrons inside a new type of semiconductor material.

When a laser strikes the electron, it reveals which way it is spinning by emitting one or more quanta, or particles, of light.

Those spin states replace the ones and zeros of traditional computing.

In her studies of nearly 20 years, Vuckovic has focused on one aspect of the challenge: creating new types of quantum computer chips that would become the building blocks of future systems, Xinhua reported.

The challenge is developing materials that can trap a single, isolated electron.

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To address the problem, the Stanford researchers have recently tested three different approaches, one of which can operate at room temperature, in contrast to what some of the world's leading technology companies are trying with materials super-cooled to near absolute zero, the theoretical temperature at which atoms would cease to move.

In all three cases, the researchers started with semiconductor crystals, namely materials with a regular atomic lattice-like the girders of a skyscraper.

By slightly altering this lattice, they sought to create a structure in which the atomic forces exerted by the material could confine a spinning electron.

One way to create the laser-electron interaction chamber is through a structure known as a quantum dot or a small amount of indium arsenide inside a crystal of gallium arsenide.

The atomic properties of the two materials are known to trap a spinning electron.

In a paper published in Nature Physics, Kevin Fischer, a graduate student in the Vuckovic lab, describes how the laser-electron processes can be exploited within such a quantum dot to control the input and output of light.

By sending more laser power to the quantum dot, the researchers could force it to emit exactly two photons rather than one. It has advantages over other leading quantum computing platforms but still requires cryogenic cooling.

So, the result may not be useful for general-purpose computing, but quantum dot could have applications in creating tamper-proof communications networks.

Also read: Ransomware Decrypted: French Researchers Find a Way to Save WannaCry Encrypted Windows Files

Another way to electron capture, as Vuckovic and her colleagues have investigated in two other cases, is to modify a single crystal to trap light in what is called a colour centre.

In a paper published in NanoLetters, Jingyuan Linda Zhang, a graduate student in Vuckovic's lab, described how a 16-member research team replaced some of the carbon atoms in the crystalline lattice of a diamond with silicon atoms.

The alteration created colour centres that effectively trapped spinning electrons in the diamond lattice.

Like the quantum dot, however, most diamond colour centre experiments require cryogenic cooling.

But the field is still in its early days, and the researchers aren't sure which method or methods will win out.

"We don't know yet which approach is best, so we continue to experiment," Vuckovic noted.

Also read: New Nano-Material to Help Curb Pollution From Vehicles

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Quantum Computing Research Given a Boost by Stanford Team - News18

San Francisco, May 21 (IANS) Stanford University electrical engineering Professor Jelena Vuckovic and colleagues at her laboratory are working on new materials that could become the basis for quantum computing.

While silicon transistors in traditional computers push electricity through devices to create digital ones and zeros, quantum computers work by isolating spinning electrons inside a new type of semiconductor material.

When a laser strikes the electron, it reveals which way it is spinning by emitting one or more quanta, or particles, of light.

Those spin states replace the ones and zeros of traditional computing.

In her studies of nearly 20 years, Vuckovic has focused on one aspect of the challenge: creating new types of quantum computer chips that would become the building blocks of future systems, Xinhua reported.

The challenge is developing materials that can trap a single, isolated electron.

To address the problem, the Stanford researchers have recently tested three different approaches, one of which can operate at room temperature, in contrast to what some of the world's leading technology companies are trying with materials super-cooled to near absolute zero, the theoretical temperature at which atoms would cease to move.

In all three cases, the researchers started with semiconductor crystals, namely materials with a regular atomic lattice like the girders of a skyscraper.

By slightly altering this lattice, they sought to create a structure in which the atomic forces exerted by the material could confine a spinning electron.

One way to create the laser-electron interaction chamber is through a structure known as a quantum dot, or a small amount of indium arsenide inside a crystal of gallium arsenide.

The atomic properties of the two materials are known to trap a spinning electron.

In a paper published in Nature Physics, Kevin Fischer, a graduate student in the Vuckovic lab, describes how the laser-electron processes can be exploited within such a quantum dot to control the input and output of light.

By sending more laser power to the quantum dot, the researchers could force it to emit exactly two photons rather than one. It has advantages over other leading quantum computing platforms but still requires cryogenic cooling.

So, the result may not be useful for general-purpose computing, but quantum dot could have applications in creating tamper-proof communications networks.

Another way to electron capture, as Vuckovic and her colleagues have investigated in two other cases, is to modify a single crystal to trap light in what is called a colour centre.

In a paper published in NanoLetters, Jingyuan Linda Zhang, a graduate student in Vuckovic's lab, described how a 16-member research team replaced some of the carbon atoms in the crystalline lattice of a diamond with silicon atoms.

The alteration created colour centres that effectively trapped spinning electrons in the diamond lattice.

Like the quantum dot, however, most diamond colour centre experiments require cryogenic cooling.

But the field is still in its early days, and the researchers aren't sure which method or methods will win out.

"We don't know yet which approach is best, so we continue to experiment," Vuckovic noted.

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Researchers push forward quantum computing research - The ... - Economic Times

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IBM has some new options for businesses wanting to experiment with quantum computing.

Quantum computers, when they become commercially available, are expected to vastly outperform conventional computers in a number of domains, including machine learning, cryptography and the optimization of business problems in the fields of logistics and risk analysis.

Where conventional computers deal in ones and zeros (bits) the processors in quantum computers use qubits, which can simultaneously hold the values one and zero. This -- to grossly oversimplify -- allows a quantum computer with a 5-qubit processor to perform a calculation for 32 different input values at the same time.

On Wednesday, IBM put a 16-qubit quantum computer online for IBM Cloud platform customers to experiment with, a big leap from the five-qubit machine it had previously made available. The company said that machine has already been used to conduct 300,000 quantum computing experiments by its cloud service users.

But that's not all: IBM now has a prototype 17-qubit system working in the labs, which it says offers twice the performance of the 16-qubit machine.

Quantum computing performance is hard to compare. Much depends on the "quality" of the qubits in the processor, which rely on shortlived atomic-level quantum phenomena and are thus somewhat unstable.

IBM is proposing a new measure of quantum computing performance that it calls quantum volume, which takes into account the interconnections between the cubits and the reliability of the calculations they perform.

The company's quantum computing division, IBM Q, has set its sights on producing a commercial 50-qubit quantum computer in the coming years.

Peter Sayer covers European public policy, artificial intelligence, the blockchain, and other technology breaking news for the IDG News Service.

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IBM makes leap in quantum computing power - ITworld

May 19, 2017 by Chris Sciacca Johannes Gooth is a postdoctoral fellow in the Nanoscale Devices & Materials group of the Science & Technology department at IBM Research Zurich. His research is focused on nanoscale electronics and quantum physics. Credit: IBM Research

IBM scientists have achieved an important milestone toward creating sophisticated quantum devices that could become a key component of quantum computers. As detailed in the peer-review journal Nano Letters, the scientists have shot an electron through a III-V semiconductor nanowire integrated on silicon for the first time.

IBM scientists are driving multiple horizons in quantum computing, from the technology for the next decade based on superconducting qubits, towards novel quantum devices that could push the scaling limit of today's microwave technology down to the nanometer scale and that do not rely on superconducting components, opening a path towards room-temperature operation.

Now, IBM scientists in Zurich have made a crucial fundamental breakthrough in their paper Ballistic one-dimensional InAs nanowire cross-junction interconnects. Using their recently developed Template-Assisted-Selective-Epitaxy (TASE) technique to build ballistic cross-directional quantum communication links, they pioneered devices which can coherently link multiple functional nanowires for the reliable transfer of quantum information across nanowire networks. The nanowire acts as a perfect guide for the electrons, such that the full quantum information of the electron (energy, momentum, spin) can be transferred without losses.

By solving some major technical hurdles of controlling the size, shape, position and quality of III-V semiconductors integrated on Si, ballistic one-dimensional quantum transport has been demonstrated. While the experiments are still on a very fundamental level, such nanowire devices may pave the way towards fault-tolerant, scalable electronic quantum computing in the future.

The paper's lead author, IBM scientist Dr. Johannes Gooth, noted that the milestone has implications for the development of quantum computing. By enabling fully ballistic connections where particles are in flight at the nanoscale, the quantum system offers exponentially larger computational space.

Earlier this year, IBM launched an industry-first initiative to build commercially available universal quantum computing systems. The planned "IBM Q" quantum systems and services will be delivered via the IBM Cloud platform and will deliver solutions to important problems where patterns cannot be seen by classical computers because the data doesn't exist and the possibilities needed to explore to get to the answer are too enormous to ever be processed by classical systems.

Explore further: Five ways quantum computing will change the way we think about computing

More information: Johannes Gooth et al. Ballistic One-Dimensional InAs Nanowire Cross-Junction Interconnects, Nano Letters (2017). DOI: 10.1021/acs.nanolett.7b00400

Journal reference: Nano Letters

Provided by: IBM

While technologies that currently run on classical computers, such as Watson, can help find patterns and insights buried in vast amounts of existing data, quantum computers will deliver solutions to important problems where ...

IBM announced today it has successfully built and tested its most powerful universal quantum computing processors. The first new prototype processor will be the core for the first IBM Q early-access commercial systems. The ...

The global race towards a functioning quantum computer is on. With future quantum computers, we will be able to solve previously impossible problems and develop, for example, complex medicines, fertilizers, or artificial ...

A team of researchers from Australia and the UK have developed a new theoretical framework to identify computations that occupy the 'quantum frontier'the boundary at which problems become impossible for today's computers ...

IBM has announced its plans to begin offering the world's first commercial universal quantum-computing servicecalled IBM Q, the system will be made available to those who wish to use it for a fee sometime later this year. ...

What does the future hold for computing? Experts at the Networked Quantum Information Technologies Hub (NQIT), based at Oxford University, believe our next great technological leap lies in the development of quantum computing.

Researchers have developed the world's thinnest metallic nanowire, which could be used to miniaturise many of the electronic components we use every day.

IBM scientists have achieved an important milestone toward creating sophisticated quantum devices that could become a key component of quantum computers. As detailed in the peer-review journal Nano Letters, the scientists ...

Rice University scientists have created a rechargeable lithium metal battery with three times the capacity of commercial lithium-ion batteries by resolving something that has long stumped researchers: the dendrite problem.

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bitsor qubitsthat are stable, meaning they are not much affected by changes in their environment. This normally needs ...

Nanocrystals have diverse applications spanning biomedical imaging, light-emitting devices, and consumer electronics. Their unique optical properties result from the type of crystal from which they are composed. However, ...

Today's computers are faster and smaller than ever before. The latest generation of transistors will have structural features with dimensions of only 10 nanometers. If computers are to become even faster and at the same time ...

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IBM scientists demonstrate ballistic nanowire connections, a potential future key component for quantum computing - Phys.Org

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When it comes toquantum computing, mostly I get excited about experimental results rather than ideas for new hardware. New devicesor new ways to implement old devicesmay end up being useful,but we won'tknow for sure when the results are in. If we are to grade existing ideas by their usefulness, then adiabatic quantum computing has to beright up there, since you can use it to perform some computations now. And at this point, adiabatic quantum computing has the best chance of getting the number of qubits up.

But qubits aren't everythingyou also need speed. Sohow, exactly, do you compare speeds between quantum computers? If you begin looking into thisissue, you'll quickly learnit's far more complicated than anyone really wanted it to be. Even when you can compare speeds today, you also want to be able to estimate how much better you could do with an improved version of the same hardware. This, it seems, often proveseven more difficult.

Unlike classical computing, speed itself is not so easy to define for a quantum computer. If we just take something like D-Wave's quantum annealer as an example, it has no system clock, and it doesn't use gates that perform specific operations. Instead, the whole computer goes through a continuous evolution from the state in which it was initialized to the state that, hopefully, contains the solution. The time that takesis called the annealing time.

At this point, you can all say, "Chris ur dumb, clearly the time from initialization to solution is what counts." Except, I used the word hopefully in that sentence above for good reason. No matter how a quantum computer is designed and operated, the readout process involves measuring the states of the qubits. That means there is a non-zero probability of getting the wrong answer.

This does not mean that a quantum computer is useless. First, for some calculations, it is possible to check a solution very efficiently. Finding prime factors is a good example. I simply multiply the factors together; if the answer doesn't come to the number I initialized the computer with, I know it got it wrong. In case of a wrong answer, I simply repeat the computation. When you can't efficiently check the solution, you can rely on statistics: the correct answer is the most probable outcome of any measurement of the final state. I can just run the same computation multiple times and determine the correct answer from the statistical distribution of the results.

So for an adiabatic quantum computer, this means speed is the annealing time multiplied by the number of runs required to determine the most probable outcome. While notthe most satisfactory answer, it's stillbetter than nothing.

Unfortunately, these two factors are not independent of each other. During annealing, the computation requires that all the qubits stay in the ground state. However, fast changes are more likely to disturb the qubits out of the ground stateso decreasing the annealing time increases the probability of getting an incorrect result. Do the work faster, andyou may need to perform the computation more times to correctly determine the most probable outcome. And as you decrease the annealing time, wrong answers will eventually become so probable that they are indistinguishable from correct answers.

Sodetermining the annealing time of an adiabatic quantum computer has something of a trial-and-error approach to it. The underlying logic is that slower is probably better, but we'll go as fast as we dare. A new paperpublished inPhysical Review Lettersshows that, actually, under the right conditions, it might be better to throw caution to the wind and speed up even more. However, that speed comes at the cost of high peak power consumption.

To recap,in an adiabatic quantum computer, the qubits are all placed in the ground state of some simple global environment. That environment is then modified such that the ground state is the solution to some problem that you want to solve. Now, provided that the qubits remain in the ground state as you change the environment, you will then obtain the correct solution.

The key liesin how fast you are allowed to modify the environment. If you do it very slowly, someone with a slide rule might beat you to the answer. If you do it very fast, your computation is likely to go wrong because the qubits leave the ground state. Fast modifications also require high peak power, so there is a trade-off between speed, power, and accuracy.

To understand the trade-off, let's use an example. Imagine the equivalent of a quantum ball and spring, otherwise known as the harmonic oscillator. In its lowest energy state, the oscillator is bouncing up and down with some natural frequency, which is given by the stiffness of the spring and the mass of the oscillator. In this case, changing the environment would mean increasing or decreasing the stiffness of the spring. To complete the analogy, the jumps between different quantum states increase and decrease the amplitude of oscillation, but those jumps don't change the frequency.

Next, imagine that we reduce the stiffness of the spring, making the system a bit floppier. The oscillation frequency slows, and the amplitude should also drop, but it will take a little time. If the pace of reduction is too fast, then the amplitude remains high for a moment, corresponding more closelyto an excited state. As a result, the oscillator might leave the ground state.

To avoid this, we have to change the spring stiffness at a rate that is slow enough for the oscillator to bleed off the excess energy. Likewise, if we tighten the spring, the process gives energy to the oscillator. If we give it all that energy in one big lump, then it will be sufficient for the oscillator to jump to the excited state, if only briefly.

You can also think of this in terms of power. Although we might change the stiffness of the spring between two values, and therefore expend some amount of energy, the total power depends on how fast we make that change. A short sharp change requires high power, while a long slow change requires low power. So, you can think of three parameters that should be optimized: the speed of the change, the power consumption to complete the change, and the chance that the change drives the qubit out of the ground state.

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The route to high-speed quantum computing is paved with error - Ars Technica UK

If you're not ready to start using quantum computing in your enterprise, you should at least be planning how to do so.

Researchers say companies may be less than five to 10 years away from turning to quantum computing to solve big business problems.

David Schatsky, managing director, Deloitte LLP

"Quantum computing has the potential to not just do things faster but to allow companies to do things entirely differently," said David Schatsky, managing director of Deloitte LLP, a global consulting and financial advisory company. "If they have certain analytical workloads that could take them weeks to run and they could do it almost instantaneously, how would that change the way they make decisions, or the risks they're willing to take or what products and services they can offer customers?"

That means corporate execs and IT heads should be thinking now about the strategic and operational implications of having quantum computers in their tech toolbox.

There is much buzz around quantum computers because they are expected to surpass even the most powerful classic supercomputers in certain calculations -- especially handling problems that involve sifting through massive amounts of data. Quantum computers, for example, might be able to find distant habitable planets, the cure for cancer and Alzheimer's disease or revamp complex airline flight schedules.

Quantum machines offer a different kind of computing power because instead of relying on ones and zeros - or bits - they use qubits, which can be both ones and zeros.

One of the rules of quantum mechanics is that a quantum system can be in more than one state at the same time, meaning it's not known what a qubit is until it begins to interact with -- or entangle -- other qubits. Unlike classic computers that operate in a linear or orderly fashion, quantum computers gain their power from qubits working with each other, allowing them to calculate all possibilities at the same time, instead of one by one.

"It's an incredibly promising new paradigm in computing," said William Martin, a math professor at Worcester Polytechnic Institute in Worcester, Mass. "We have examples of things a quantum computer can do that we don't know how to do with a normal computer. It's going to be a game-changing phenomenon, if we can actually build it."

WPI professor William Martin

In a report released late last month, Deloitte noted that quantum computing is close to realizing its promise and having an enormous impact on fields from healthcare to pharmaceuticals, space exploration and manufacturing. As researchers continue work on building powerful, fully functional quantum machines, interest is growing.

The field has attracted $147 million in venture capital in the last three years and $2.2 billion in government funding globally, according to Deloitte.

A little over a year ago, the European Commission announced a $1.13 billion project to develop quantum technologies over the next decade. And the Chinese Academy of Sciences announced last month that it is working to build a quantum computer in the next several years.

The U.S. is considered to be a major investor in quantum computing research, as well as home to quantum-focused companies like IBM, Google and Microsoft. . Google, for instance, is working on quantum processes it can make available to companies over the cloud, while Microsoft said last fall it was ready to go from "research to engineering with its quantum work."

There also are quantum computing startups like Rigetti Computing, 1Qbit, and Cambridge Quantum Computing, that are getting a lot of attention.

They're not all building a large quantum computer. Some are working on software, while others focus on hardware components or quantum-resistant cryptography.

One company now building what its executives say is the first quantum computer is D-Wave Systems, based in Burnaby, British Columbia.

Although many question whether it's a true quantum computer, D-Wave's system is still being tested by the likes of NASA, Google, the Los Alamos National Laboratory and Lockheed Martin. That level of interest in testing the D-Wave system - whether it's a true quantum computer or not -- shows how high expectations have gotten around this technology.

Rupak Biswas, director of exploration technology at NASA Ames Research Center, said he oversees 700 employees -- 10 to 12 of whom are now working on quantum computing. Those efforts include testing the D-Wave system.

About $3 million of the agency's research-and-development budget goes to quantum computing.

While NASA is not yet trying to solve real problems - like massive air traffic management issues or scheduling astronaut time on the International Space Station - scientists there are working to figure out the best way to use a quantum computer and understand the underlying physics, as well as the programming that will be needed for it.

Even if the D-Wave system is better at computational-heavy calculations, it's not big enough to handle real problems for NASA. Something that large could be five to 10 years away, Biswas said.

In addition to testing the D-Wave system, NASA is also working with U.C. Berkeley, Google, U.C. Santa Barbara, Rigetti Computing, and Sandia National Labs - all of which are doing quantum research.

"Our focus is how do we use available technology to accelerate our main mission," said Biswas. "Quantum computing is an enabling technology. We're looking now at what it will let us do."

That plan follows the advice Deloitte's Schatsky is giving to large enterprises.

"I'd expect to see some meaningful commercial use in the next 10 years," said Schatsky. "We're not saying that companies will be buying quantum computers in the next 'n' years, but this is a real phenomenon that is progressing rapidly.... Companies should pay attention and should start to think about the strategic and operational implications of having this.

"I don't think it's worth a huge amount of time in the C-suite, but if [a company] is innovative and forward looking, they should be tracking this phenomenon, and if they have an R&D budget, they should allocate a slice of it to this domain," said Schatsky, noting that some banks have invested a few million dollars in quantum R&D. "I think interest is going to grow."

Dario Gil, vice president of Science and Solutions at IBM Research, has been working on quantum computing there for the last five years, though the company itself has been researching it since the 1970s.

A year ago, IBM announced it not only had a 5-qubit processor but was making it available to customers in the cloud.

According to Gil, IBM has had about 45,000 universities and companies running more than 300,000 experiments on the cloud-based quantum system. Those efforts are not designed to solve production problems but to learn how to work with a quantum machine.

"I absolutely agree that now is the right time to start thinking about quantum," said Gil. "Companies already are and they are engaging very seriously on this topic. I think quantum, for any serious company that relies on computing for their business, can't just be something that is out there on the horizon. At least one person in your organization should be thinking about what is this and what does it mean for this organization?"

He added that IBM is focused on trying to make quantum machines that can be, or routinely are, used on real-world problems in the enterprise within the next three to five years.

"We're already in that window of quantum emerging as a technology that has commercial value," said Gil. "If you were thinking about the web in the early 1990s or mobile in the early 2000s, this is analogous. Nobody would look back and say, 'I wish I had slowed down in my thinking about those technolgies. You have to start understanding about what it is and what it can do."

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It's time to decide how quantum computing will help your business - Techworld Australia

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IBM has some new options for businesses wanting to experiment with quantum computing.

Quantum computers, when they become commercially available, are expected to vastly outperform conventional computers in a number of domains, including machine learning, cryptography and the optimization of business problems in the fields of logistics and risk analysis.

Where conventional computers deal in ones and zeros (bits) the processors in quantum computers use qubits, which can simultaneously hold the values one and zero. Thisto grossly oversimplifyallows a quantum computer with a 5-qubit processor to perform a calculation for 32 different input values at the same time.

On Wednesday, IBM put a 16-qubit quantum computer online for IBM Cloud platform customers to experiment with, a big leap from the five-qubit machine it had previously made available. The company said that machine has already been used to conduct 300,000 quantum computing experiments by its cloud service users.

But thats not all: IBM now has a prototype 17-qubit system working in the labs, which it says offers twice the performance of the 16-qubit machine.

Quantum computing performance is hard to compare. Much depends on the quality of the qubits in the processor, which rely on shortlived atomic-level quantum phenomena and are thus somewhat unstable.

IBM is proposing a new measure of quantum computing performance that it calls quantum volume, which takes into account the interconnections between the cubits and the reliability of the calculations they perform.

The companys quantum computing division, IBM Q, has set its sights on producing a commercial 50-qubit quantum computer in the coming years.

Peter Sayer covers European public policy, artificial intelligence, the blockchain, and other technology breaking news for the IDG News Service.

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IBM makes a leap in quantum computing power - PCWorld

In BriefIBM has announced that it has built and tested its two mostpowerful platforms for quantum computing to date. Members of thepublic can request beta access to use the 16 qubit platform to runexperiments and help propel quantum computing technology forward. Quantum Computing Leaps

Due to their complexity, quantum computers are still largely inaccessible for the average person, which is why developers and programmers jumped at the chance to test out IBMs five qubit quantum computing processor when the company offered thepublic free access to it last year, running more than 300,000 experiments on the cutting-edge machine.

Now, the company is taking the tech to the next level, announcing yesterdaythat it has built and tested its two most powerful platforms for quantum computing to date: the 16 qubit Quantum Experience universal computer and a 17 qubit commercial processor prototype that will serve as the core for its IBM Q commercial system.

IBMs 16 qubit processor will make far more complex computations possible without breaking a symbolic quantum sweat. Once again, the company is hoping that developers, programmers, researchers, and anyone working in the field will make use of the platform. To that end, anyone interested in using it for experiments to help usher in the age of quantum computingis encouraged tovisit GitHubs Software Development Kit to request beta access. Otherwise, they can simply access theIBM experience libraryto play around with the technology.

Of course, IBM is far from satisfied with just 16 or 17 qubits. The company hopes to significantly ratchet up the power with a goal of achieving a 50 qubit quantum computing platform or maybe one with even more power in the next few years.

Quantum computing technology has the capacity to solving extraordinarily complex problems problems that in many cases may be difficult for us to even conceive of right now. This potential has been propelling research forward at a remarkable rate, with researchers smashing through milestone after milestone along the path toward commercial quantum computing.

In August 2016, a quantum logic gate with an amazing 99.9 percent precision was achieved, removing a critical theoretical benchmark. Meanwhile, researchers used microwave signals to encode quantum computing data, offering an alternative to optical solutions. In October 2016, researchers used silicon atoms to produce qubits that remained in stable superposition 10 times longer than any qubits before them.

However, as each technical barrier has fallen, the need for public collaboration has become more apparent. In January, Canadian quantum computing company D-Waveopen-sourced its own quantum software tool, Qbsolv, allowing programmers to work on a quantum system whether or not they had any prior experience withquantum computing. With IBM now offering an even-more-powerfulsystem for experimentation, the public now has at its disposal a tool that could lead to remarkable advancements in nearly every field imaginable. As experts have announced, we truly are now living in the age of quantum computing.

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IBM's Newest Quantum Computing Processors Have Triple the Qubits of Their Last - Futurism

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