Category Archives: Quantum Computer

How Quantum Computers Work

A quantum computer is a computer design which uses the principles of quantum physics to increase the computational power beyond what is attainable by a traditional computer. Quantum computers have been built on the small scale and work continues to upgrade them to more practical models.

Computers function by storing data in a binary number format, which result in a series of 1s & 0s retained in electronic components such as transistors.

Each component of computer memory is called a bit and can be manipulated through the steps of Boolean logic so that the bits change, based upon the algorithms applied by the computer program, between the 1 and 0 modes (sometimes referred to as “on” and “off”).

A quantum computer, on the other hand, would store information as either a 1, 0, or a quantum superposition of the two states. Such a “quantum bit” allows for far greater flexibility than the binary system.

Specifically, a quantum computer would be able to perform calculations on a far greater order of magnitude than traditional computers … a concept which has serious concerns and applications in the realm of cryptography & encryption. Some fear that a successful & practical quantum computer would devastate the world’s financial system by ripping through their computer security encryptions, which are based on factoring large numbers that literally cannot be cracked by traditional computers within the lifespan of the universe.

A quantum computer, on the other hand, could factor the numbers in a reasonable period of time.

To understand how this speeds things up, consider this example. If the qubit is in a superposition of the 1 state and the 0 state, and it performed a calculation with another qubit in the same superposition, then one calculation actually obtains 4 results: a 1/1 result, a 1/0 result, a 0/1 result, and a 0/0 result.

This is a result of the mathematics applied to a quantum system when in a state of decoherence, which lasts while it is in a superposition of states until it collapses down into one state. The ability of a quantum computer to perform multiple computations simultaneously (or in parallel, in computer terms) is called quantum parallelism).

The exact physical mechanism at work within the quantum computer is somewhat theoretically complex and intuitively disturbing. Generally, it is explained in terms of the multi-world interpretation of quantum physics, wherein the computer performs calculations not only in our universe but also in other universes simultaneously, while the various qubits are in a state of quantum decoherence. (While this sounds far-fetched, the multi-world interpretation has been shown to make predictions which match experimental results. Other physicists have )

Quantum computing tends to trace its roots back to a 1959 speech by Richard P. Feynman in which he spoke about the effects of miniaturization, including the idea of exploiting quantum effects to create more powerful computers. (This speech is also generally considered the starting point of nanotechnology.)

Of course, before the quantum effects of computing could be realized, scientists and engineers had to more fully develop the technology of traditional computers. This is why, for many years, there was little direct progress, nor even interest, in the idea of making Feynman’s suggestions into reality.

In 1985, the idea of “quantum logic gates” was put forth by University of Oxford’s David Deutsch, as a means of harnessing the quantum realm inside a computer. In fact, Deutsch’s paper on the subject showed that any physical process could be modeled by a quantum computer.

Nearly a decade later, in 1994, AT&T’s Peter Shor devised an algorithm that could use only 6 qubits to perform some basic factorizations … more cubits the more complex the numbers requiring factorization became, of course.

A handful of quantum computers has been built.

The first, a 2-qubit quantum computer in 1998, could perform trivial calculations before losing decoherence after a few nanoseconds. In 2000, teams successfully built both a 4-qubit and a 7-qubit quantum computer. Research on the subject is still very active, although some physicists and engineers express concerns over the difficulties involved in upscaling these experiments to full-scale computing systems. Still, the success of these initial steps does show that the fundamental theory is sound.

The quantum computer’s main drawback is the same as its strength: quantum decoherence. The qubit calculations are performed while the quantum wave function is in a state of superposition between states, which is what allows it to perform the calculations using both 1 & 0 states simultaneously.

However, when a measurement of any type is made to a quantum system, decoherence breaks down and the wave function collapses into a single state. Therefore, the computer has to somehow continue making these calculations without having any measurements made until the proper time, when it can then drop out of the quantum state, have a measurement taken to read its result, which then gets passed on to the rest of the system.

The physical requirements of manipulating a system on this scale are considerable, touching on the realms of superconductors, nanotechnology, and quantum electronics, as well as others. Each of these is itself a sophisticated field which is still being fully developed, so trying to merge them all together into a functional quantum computer is a task which I don’t particularly envy anyone …

except for the person who finally succeeds.

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How Quantum Computers Work

This is what a 50-qubit quantum computer looks like

That’s where the pumps would normally come in. From top to bottom, the system gradually cools from four Kelvin — liquid-helium temperatures — to 800 milliKelvin, 100 milliKelvin and, finally, 10 milliKelvin. Inside the canister, that’s 10 thousandths of a degree above absolute zero. The wires, meanwhile, carry RF-frequency signals down to the chip. These are then mapped onto the qubits, executing whatever program the research team wishes to run. The wiring is also designed in a way to ensure that no extraneous noise — including heat — is transported to the quantum computer chip at the bottom.

Many in the industry have suggested that a 50-qubit system could achieve “quantum supremacy.” The term refers to the moment when a quantum computer is able to outperform a traditional system or accomplish a task otherwise thought impossible. The problem, though, is that quantum computers are only compatible with certain algorithms. They’re well-suited to quantum chemistry, for instance, and material simulations. But it’s unlikely you’ll ever use a quantum computer to complete a PowerPoint presentation. “The world is not classical, it’s quantum, so if you want to simulate it you need a quantum computer,” Welser said.

Researchers have already conducted experiments with quantum computers. Scientists at IBM were able to simulate beryllium hydride (BeH2) on a seven-qubit quantum processor last September, for example. But critics want to see a quantum computer accomplish something more tangible, which is more meaningful for the everyday consumer. That day, unfortunately, could still be a long way off.

“Somewhere between 50 and 100 qubits, we’ll reach the point where we can at least say very clearly, ‘I’ve just simulated a molecule here in a few minutes time that would have taken this giant system five days to do.’ That level we’ll be at fairly rapidly. When it gets to something that the public will understand in terms of an application they would use themselves, I can’t really speculate at this point,” Welser said.

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This is what a 50-qubit quantum computer looks like

Inside Microsofts quantum computing world | InfoWorld

Quantum computers are the future, says Microsoft CEO Satya Nadella. And he has put Microsofts money where his mouth is, making quantum computing one of the three pillars of Microsofts strategy going forward. Along with AI and mixed/augmented reality, its an area where Nadella believes that Microsoft can make a significant impact, and where it can differentiate itself from its competition.

But building a quantum computer is hard. Microsofts current progress is the result of more than 20 years of research investment, working with universities around the world, mixing pure physics with computer science, and turning experimental ideas into products. Theres a lot of ambition here, with the eventual aim of building scalable quantum computers that anyone can use.

Microsofts approach to quantum computing differs from the technologies used by companies like DWave, taking a new approach to creating the qubits, the quantum bits at the heart of the process. Working with university researchers, Microsoft has been exploring use of a new type of particle, the Majorana fermion. Initially proposed in the late 1930s, Marjorana particles have only recently been detected in semiconductor nanowires at very low temperatures.

Compared to other qubit approaches, the Majorana particles used by Microsofts quantum computers are more stable and have lower error rates, spreading out the electron state across a topological knot thats less likely to evaporate when its state is read. This topological approach to quantum computing is something that Nadella calls a transistor moment for quantum computers. It might not be the quantum processor, but its the first step on that road.

Working with a quantum computer is very different from the machines we use today. A bits 1s and 0s are replaced by a qubit with a statistical blur of fractionalized electrons that needs interpretation. With qubits temperatures at near absolute zero, another specialised low-temperature (cryogenic) computer is used to program the qubits and read results, working with quantum algorithms to solve complex problemsand promising nearly instantaneous answers to problems that could take thousands, or even millions, of years with a modern supercomputer.

You can think of the relationship between the cryogenic controller and programs running on the ultralow-temperature quantum computer as something akin to how deep-sea divers work on underwater oil rigs. The quantum computer is the well head, isolated from the rest of the world by temperature. That makes the cryogenic control computer the equivalent of a divers pressurized diving bell, giving the programs a stepping stone between the normal temperatures of the outside world and the extreme cold of the quantum refrigerator, much like how a diving bell prepares divers for working at extreme depths.

Microsofts quantum computers are unlikely to run in your own datacenters. They require specialized refrigerators to chill the qubits, which are built from carefully grown nanowires. Microsofts consortium of universities can manufacture each part separately, bringing them together to deliver the current generation of test systems.

Microsoft intends to embed its quantum hardware in Azure, running a quantum simulator to help test quantum code before its deployed to actual quantum computers. Microsoft is also working on a new language to help developers write quantum code in Visual Studio.

Microsoft Research has already delivered a first cut at a quantum programming environment in Liqui|> (usually referred to as Liquid), a set of tools to simulate a 30-qubit environment on a PC with 32GB of memory. Microsoft says youll be able to deploy large quantum simulators with more than 40 qubits in 16TB on Azure, though solving problems of that size will take a long time without the acceleration of a real quantum computer.

Still, with Liquid, you can experiment with key quantum computing concepts using F#, seeing how youll build algorithms to handle complex mathematical concepts, as well as understanding how to work with low-level error-correction algorithms.

Microsofts new quantum computing language will build on lessons learned with Liquid, but it wont be based on F#. The languages name hasnt been revealed yet, but amusingly some early screenshots of quantum code being edited in Visual Studio appeared to use the same file extension as the classic Quick Basic.

I recently spoke with Krysta Svore, the lead of Microsoft Research s Redmond Quantum computing group, which works on building the software side of Microsofts planned scalable quantum computer. Its a fascinating side of the project, taking the low-level quantum algorithms needed to work with experimental hardware and finding ways of generating them from familiar high-level languages. If Svores team is successful, you wont need to know about the quantum computer youre programming; instead, youll write code, publish it to Azure, and run it.

The goal is that youll be able to concentrate on your code, not think about the underlying quantum circuitry. For example, instead of building the connections needed to construct a quantum Fourier transform, youll call a QFT library, writing additional code to prepare, load, and read data. As Svore notes, many quantum algorithms are hybrids, mixing preprocessing and postprocessing with quantum actions, often using them as part of loops run in a classical supercomputer.

Theres also a role for AI techniques, using machine learning to identify elements of code, understanding where and how they work best.

Developers who experiment with Liquid will be able to bring their applications to the new platform, with migration tools to help with the transition. Using the Azure-based quantum simulator should help, because it supports many more qubits than a PC does. Itll also let you explore working with execution-based parallelism, where you run multiple passes over the same data, rather than the more familiar GPGPU data parallelism model.

You can get a feel for what this means for computing when you consider an 80-qubit operation. Svore notes that a single operation in a quantum computer takes 100ns, no matter how many qubits you have. The same operation in a classical computer would require more particles than in the visible universe, taking longer than the lifetime of the universe. Solving that type of problem in 100ns is a huge leap forward, one that opens new directions for scientific computing.

Microsofts quantum computing work is a big bet on the future of computing. Today, its a long way from every day use, still in the domain of pure research, even if that research is coming up with promising results.

Where Microsofts quantum-computing work really will make a difference is if it can deliver a programming environment that will let us take hard problems and turn them into quantum algorithms quickly and repeatedly, without having to go beyond the familiar world of IDEs and parallel programming constructs. Getting that right will really change the world, in ways we cant yet imagine.

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Inside Microsofts quantum computing world | InfoWorld

Microsoft Takes Path Less Traveled to Build a Quantum …

In the race to commercialize a new type of powerful computer, Microsoft Corp. has just pulled up to the starting line with a slick-looking set of wheels. Theres just one problem: it doesn’t have an engine at least not yet.

The Redmond, Washington-based tech giant is competing with Alphabet Inc.s Google, International Business Machines Corp. and a clutch of small, specialized companies to develop quantum computers machines that, in theory, will be many times more powerful than existing computers by bending the laws of physics.

Microsoft says it has a different approach that will make its technology less error-prone and more suitable for commercial use. If it works. On Monday, the company unveiled a new programming language called Q# pronounced Q Sharp and tools that help coders craft software for quantum computers. Microsoft is also releasing simulators that will let programmers test that software on a traditional desktop computer or through its Azure cloud-computing service.

The machines are one of the advanced technologies, along with artificial intelligence and augmented reality, that Microsoft Chief Executive Officer Satya Nadella considers crucial to the future of his company. Microsoft, like IBM and Google, will most likely rent computing time on these quantum machines through the internet as a service.

D-Wave Systems Inc. in 2011 became the first company to sell a quantum computer, although its technology has been controversial and can only perform a certain subset of mathematical problems. Google and IBM have produced machines that are thought to be close to achieving quantum supremacy the ability to tackle a problem too complex to solve on any standard supercomputer. IBM and startup Rigetti Computing also have software for their machines.

Microsoft, in contrast, is still trying to build a working machine. It is pursuing a novel design based on controlling an elusive particle called a Majorana fermion that no one was sure even existed a few years ago. Engineers are close to being able to control the Majorana fermionin a way that will enable them to perform calculations, Todd Holmdahl, head of Microsofts quantum computing efforts, said in an interview. Holmdahl, who led development of the Xbox and the company’s HoloLens goggles, said Microsoft will have a quantum computer on the market within five years.

We are talking to multiple customers today and we are proposing quantum-inspired services for certain problems, he added.

These systems push the boundaries of how atoms and other tiny particles work. While traditional computers process bits of information as 1s or zeros, quantum machines rely on “qubits” that can be a 1 and a zero at the same time. So two qubits can represent four numbers simultaneously, and three qubits can represent eight numbers, and so on. This means quantum computers can perform calculations much faster than standard machines and tackle problems that are way more complex.

Krysta Svore

Source: Microsoft

Applications could include things like creating new drugs and new materials or solving complex chemistry problems. The killer app of quantum computing is discovering a more efficient way to synthesize ammonia for fertilizer a process that currently consumes three percent of the worlds natural gas, according to Krysta Svore, who oversees the software aspects of Microsofts quantum work.

The technology is still emerging from a long research phase, and its capabilities are hotly debated. Researchers have only been able to keep qubits in a quantum state for fractions of a second. When qubits fall out of a quantum state they produce errors in their calculations, which can negate any benefit of using a quantum computer.

Microsoft says it uses a different design called a topological quantum computer that in theory will create more stable qubits. This couldproduce a machine with an error rate from 1,000 to10,000 times better than computers other companies are building, Holmdahl said.

Reducing or correcting the errors in quantum calculations is essential for the technology to fulfill its commercial potential, said Jonathan Breeze, a research fellow working on advanced materials at Imperial College London.

The lower error rate of Microsoft’s design may mean it can be more useful for tackling real applications — even with a smaller number of qubits perhaps less than 100. Svore said her team has already proven mathematically that algorithms that use a quantum approach can speed up machine learning applications substantially enabling them to run as much as 4,000 times faster. (Machine learning is a type of artificial intelligence behind recent advances in computers ability to identify objects in images, translate languages and drive cars).

“We want to solve today’s unsolvable problems and we have an opportunity with a unique, differentiated technology to do that,” Holmdahl said.

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Microsoft Takes Path Less Traveled to Build a Quantum …

Researchers create new type of quantum computer | Harvard Gazette

Programming a computer is generally a fairly arduous process, involving hours of coding, not to mention the laborious work of debugging, testing, and documenting to make sure it works properly.

But for a team of physicists from the Harvard-MIT Center for Ultracold Atoms and the California Institute of Technology, things are actually much tougher.

Working in a Harvard Physics Department lab, a team of researchers led by Harvard Professors Mikhail Lukin and Markus Greiner and Massachusetts Institute of Technology Professor Vladan Vuletic developed a special type of quantum computer, known as a quantum simulator, that is programmed by capturing super-cooled rubidium atoms with lasers and arranging them in a specific order, then allowing quantum mechanics to do the necessary calculations.

The system could be used to shed light on a host of complex quantum processes, including the connection between quantum mechanics and material properties, and it could investigate new phases of matter and solve complex real-world optimization problems. The system is described in a Nov. 30 paper published in the journal Nature.

The combination of the systems large size and high degree of quantum coherence make it an important achievement, researchers say. With more than 50 coherent qubits, this is one of the largest quantum systems ever created with individual assembly and measurement.

In the same issue of Nature, a team from the Joint Quantum Institute at the University of Maryland described a similarly sized system of cold charged ions, also controlled with lasers. Taken together, these complimentary advances constitute a major step toward large-scale quantum machines.

Everything happens in a small vacuum chamber where we have a very dilute vapor of atoms which are cooled close to absolute zero, Lukin said. When we focus about 100 laser beams through this cloud, each of them acts like a trap. The beams are so tightly focused, they can either grab one atom or zero; they cant grab two. And thats when the fun starts.

Using a microscope, researchers can take images of the captured atoms in real time, and then arrange them in arbitrary patterns for input.

We assemble them in a way thats very controlled, said Ahmed Omran, a postdoctoral fellow in Lukins lab and a co-author of the paper. Starting with a random pattern, we decide which trap needs to go where to arrange them into desired clusters.

As researchers begin feeding energy into the system, the atoms begin to interact with each other. Those interactions, Lukin said, give the system its quantum nature.

We make the atoms interact, and thats really whats performing the computation, Omran said. In essence, as we excite the system with laser light, it self-organizes. Its not that we say this atom has to be a one or a zero we could do that easily just by throwing light on the atoms but what we do is allow the atoms to perform the computation for us, and then we measure the results.

Those results, Lukin and colleagues said, could shed light on complex quantum mechanical phenomena that are all but impossible to model using conventional computers.

If you have an abstract model where a certain number of particles are interacting with each other in a certain way, the question is why dont we just sit down at a computer and simulate it that way? asked Ph.D. student Alexander Keesling, another co-author. The reason is because these interactions are quantum mechanical in nature. If you try to simulate these systems on a computer, youre restricted to very small system sizes, and the number of parameters are limited.

If you make systems larger and larger, very quickly you will run out of memory and computing power to simulate it on a classical computer, he added. The way around that is to actually build the problem with particles that follow the same rules as the system youre simulating. Thats why we call this a quantum simulator.

Though its possible to use classical computers to model small quantum systems, the simulator developed by Lukin and colleagues uses 51 qubits, making it virtually impossible to replicate using conventional computing techniques.

It is important that we can start by simulating small systems using our machine, he said. So we are able to show those results are correct until we get to the larger systems, because there is no simple comparison we can make.

By Peter Reuell, Harvard Staff Writer | July 3, 2012 | Editor’s Pick

When we start off, all the atoms are in a classical state. And when we read out at the end, we obtain a string of classical bits, zeros, and ones, said Hannes Bernien, another postdoctoral fellow in Lukins lab, and also a co-author. But in order to get from the start to the end, they have to go through the complex quantum mechanical state. If you have a substantial error rate, the quantum mechanical state will collapse.

Its that coherent quantum state, Bernien said, that allows the system to work as a simulator, and also makes the machine a potentially valuable tool for gaining insight into complex quantum phenomena and eventually performing useful calculations. The system already allows researchers to obtain unique insights into transformations between different types of quantum phases, called quantum phase transitions. It may also help shed light on new and exotic forms of matter, Lukin said.

Normally, when you talk about phases of matter, you talk about matter being in equilibrium, he said. But some very interesting new states of matter may occur far away from equilibrium and there are many possibilities for that in the quantum domain. This is a completely new frontier.

Already, Lukin said, the researchers have seen evidence of such states. In one of the first experiments conducted with the new system, the team discovered a coherent non-equilibrium state that remained stable for a surprisingly long time.

Quantum computers will be used to realize and study such non-equilibrium states of matter in the coming years, he said. Another intriguing direction involves solving complex optimization problems. It turns out one can encode some very complicated problems by programming atom locations and interactions between them. In such systems, some proposed quantum algorithms could potentially outperform classical machines. Its not yet clear whether they will or not, because we just cant test them classically. But we are on the verge of entering the regime where we can test them on the fully quantum machines containing over 100 controlled qubits. Scientifically, this is really exciting.

Other co-authors of the study were visiting scientist Sylvain Schwartz, Harvard graduate students Harry Levine and Soonwon Choi, research associate Alexander S. Zibrov, and Professor Manuel Endres.

This research was supported with funding from the National Science Foundation, the Center for Ultracold Atoms, the Army Research Office, and the Vannevar Bush Faculty Fellowship.

By Arthur Goldhammer, Center for European Studies | November 30, 2017

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Researchers create new type of quantum computer | Harvard Gazette

Microsoft releases quantum computing development kit preview …

At the Microsoft Ignite Conference in September, Microsoft let it be known it was going to be a player in the future of quantum computing, and today the company took another step toward that goal when it released a preview of its quantum computing development kit.

The kit includes all of the pieces a developer needs to get started including a Q# language and compiler, a Q# library, a local quantum computing simulator, a quantum trace simulator and a Visual Studio extension.

This is a preview, so its aimed at early adopters who want to understand what it takes to develop programs for quantum computers, which operate very differently from classical ones. Put in simple terms, with a classical computer, a bit can only exist in a binary state of on or off, whereas with quantum programs a qubit (the quantum equivalent of a bit) can exist in multiple states at the same time. This could open the door to programs that simply couldnt have existed before.

This is but one piece in Microsofts big vision for quantum computing that it discussed at Ignite. Microsofts Krysta Svore told TechCrunchs Frederic Lardinois in September that the idea was to offer a comprehensive full-stack solution for controlling the quantum computer and writing applications for it.

We like to talk about co-development, she said. We are developing those [the hardware and software stack] together so that youre really feeding back information between the software and the hardware as we learn, and this means that we can really develop a very optimized solution, she told Lardinois.

Microsoft clearly wants a piece of the quantum computing action, but they are hardly alone. IBM has had a quantum computing service available for programmers since last year, and last month it had a breakthrough with the release of a 20 qubit quantum computer. The company also announced a 50 qubit prototype.

Other companies working on quantum computing research include Google and Intel and a host of other established companies and startups.

We are still in very early days with this technology and it has a long way to go, but the potential is so great that all of these companies, including Microsoft, want to get in as early as possible to capture developer hearts and minds. Todays release is part of that.

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Microsoft releases quantum computing development kit preview …

Intel moves towards production quantum computing with new 17 …

Intels quantum computing efforts have yielded a new 17-qubit chip, which the company has just delivered to its partner in that field, QuTech in the Netherlands. Its not a major advance in the actual computing power or applications those are still in very early days but its a step towardproduction systems that can be ordered and delivered to spec rather than experimental ones that live in a physics lab somewhere.

Intels celebration of this particular chip is a bit arbitrary; 17 isnt some magic number in the quantum world, nor does this chip do any special tricks other quantum computer systems cant. Intel is just happy that its history and undeniable expertise in designing and fabricating chips and architectures is paying off in a new phase of computing.

I chatted with Intels director of quantum hardware, Jim Clarke, about the new system.

The test chip itself (the gold ports arent the qubits themselves, obviously)

Were relying on our expertise in hardcore engineering, he said. Were working on all parts of the compute stack: the chip, the control electronics, the system architecture, the algorithm.

Its not quite like popping out a new Core processor every year, but theres plenty of overlap.

Our infrastructure allows us to adapt the materials and the package, Clarke said. If you think of a material that might be good for a qubit chip, Intel likely already has a mature process for that material or at least experience with it.

That isnt easy when the field of computing theyre attempting to enter is largely theoretical. Thats why partners like QuTech, a research institute under TU Delft, are essential. Intel isnt short on big brains, but a dedicated facility under a major technical university is likely more fertile ground for this kind of bleeding-edge work.

The basic relationship is that Intel makes the chips, and QuTech tests them with the latest algorithms, models, and instruments. They turn around and say something like that was great, but well need at least 14 qubits to do this next thing, and we saw a lot of interference under such and such conditions. Intel jots it down and a few months later (theres no set timeline), out comes a new one, and the cycle repeats.

Im simplifying, of course, because I dont know the details of all this quantum tomfoolery (who can, really?), but thats a powerful cycle to nurture.

The results so far let Intel boast of a chip that, thanks to the companys manufacturing prowess and the work by QuTech, has considerably improved in reliability and performance over the last two years, while the architecture, system infrastructure (such as interconnects and testing methods) and so on have evolved alongside.

Of course, these amazing quantum computers still dont really do anything yet and they have to operate at around 20 thousandths of a degree above absolute zero. But the first problem is more exciting than limiting (the potential of these machines, theoretically, is enormous), and the second one, to my surprise, isnt really a big deal any more.

Turns out (perhaps you knew, but I didnt) that you can package a multi-qubit quantum computing system, cooled to the millikelvin level, in an enclosure the size of an oil drum.

Theres a long way to go in the quantum computing world, but its a no-brainer for companies like Intel to bet on the concept; its billions of dollars in infrastructure serve excellently for collateral.

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Intel moves towards production quantum computing with new 17 …

Quantum detectives in the hunt for the world’s first quantum computer – Phys.Org

Launch of the University of Sydney partnership with Microsoft.Front row: Ph.D. candidate Alice Mahoney with Microsoft’s David Pritchard. Back row (R-L): Station Q Sydney director Professor David Reilly; Microsoft’s Douglas Carmean; Station Q Sydney senior research scientist Dr. Maja Cassidy; University of Sydney Chancellor Belinda Hutchinson, postdoctoral researcher Dr. John Hornibrook and University of Sydney Vice-Chancellor Dr. Michael Spence. Credit: Jayne Ion/University of Sydney

Scientists at the University of Sydney are entering a new phase of development to scale up the next generation of quantum-engineered devices.

These devices will form the heart of the first practical topological quantum computers.

A study released today in Nature Communications confirms one of the prerequisites for building these devices.

An author of that paper, Dr Maja Cassidy, said: “Here at Station Q Sydney we are building the next generation of devices that will use quasiparticles known as Majorana fermions as the basis for quantum computers.”

Dr Cassidy said the $150 million Sydney Nanoscience Hub provides a world-class environment in which to build the next generation of devices.

Microsoft’s Station Q will move scientific equipment into the Nanoscience Hub’s clean rooms – controlled environments with low levels of pollutants and steady temperatures – over the next few months as it increases capacity to develop quantum machines.

Detective hunt

Dr Cassidy said that building these quantum devices is a “bit like going on a detective hunt”.

“When Majorana fermions were first shown to exist in 2012, there were many who said there could be other explanations for the findings,” she said.

A challenge to show the findings were caused by Majoranas was put to the research team led by Professor Leo Kouwenhoven, who now leads Microsoft’s Station Q in the Netherlands.

The paper published today meets an essential part of that challenge.

In essence, it proves that electrons on a one-dimensional semiconducting nanowire will have a quantum spin opposite to its momentum in a finite magnetic field.

“This information is consistent with previous reports observing Majorana fermions in these nanowires,” Dr Cassidy said.

She said the findings are not just applicable to quantum computers but will be useful in spintronic systems, where the quantum spin and not the charge is used for information in classical systems.

Dr Cassidy conducted the research while at the Technical University Delft in the Netherlands, where she held a post-doctorate position. She has since returned to Australia and is based at the University of Sydney Station Q partnership with Microsoft.

University of Sydney Professor David Reilly is the director of Station Q Sydney.

“This is practical science at the cutting-edge,” Professor Reilly said. “We have hired Dr Cassidy because her ability to fabricate next-generation quantum devices is second to none.”

He said Dr Cassidy was one of many great minds attracted to work at Station Q Sydney already this year. “And there are more people joining us soon at Sydney as we build our capacity.”

Professor Reilly last week won the Australian Financial Review award for Emerging Leadership in Higher Education.

Explore further: Majorana highway on a chip

More information: J. Kammhuber et al, Conductance through a helical state in an Indium antimonide nanowire, Nature Communications (2017). DOI: 10.1038/s41467-017-00315-y

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Quantum detectives in the hunt for the world’s first quantum computer – Phys.Org

Scientists Propose a New Kind of Quantum Computer, But What … – Gizmodo

There are weeks where it seems like every piece of physics news mentions quantum computingbut we are nowhere near a quantum iPhone. You probably remember that computers can consist of billions of nanometer-scale transistors etched into silicon. Those chips used to be enormous, room-sized setups where instead of transistors, there were tubes the size of light bulbs. Physicists in the quantum computing world are still trying to pick out the best vacuum tubes.

Headlines emerged today mentioning a new kind of qubit that could make quantum computers more easily. But it would help to first understand where quantum computing is overall.

Heres a quick quantum computing recap. Regular computer bits store information with a binary yes-no system, like a wire with or without a current. A quantum bit, or qubit, instead relies on the probabilistic nature of quantum mechanics: instead of yes and no, theres a pair of options with an associated probability for each. There are algorithms in science and artificial intelligence that could run more quickly or efficiently with such a computing system. There are some mechanical systems that store qubits, but theyve proven expensive, bulky, or difficult to keep in that fragile quantum state without collapsing into a classical bitwith a probability of 100 percent yes or no.

A team of researchers at the University of New South Wales in Australia and Purdue University in the US now have a blueprint for a new kind of qubit and therefore a new kind of quantum computing system, one built into silicon just like the parts of a regular computer. Such a system could potentially be important as a scaleable, space-saving qubit that stays quantum. But whether it will work remains to be seen; someone actually needs to build a computer based on it.

This design provides a realizable blueprint for scalable spin-based quantum computers in silicon, the authors write in the paper, published today in the journal Nature Communications.

The paper builds on Bruce Kanes well-known 1998 quantum computer proposal in Nature, where qubits are stored as properties of atoms, and performing computer operations is done by applying an electric field. The team proposes what they call flip-flop qubits, where a phosphorous atom sits in a silicon semiconductor. The electron and the nucleus both contain intrinsic properties called spin that can assume values called up and down (spin is a property built into particles like magnetism is built into fridge magnets). The flip-flop qubits ones and zeroes become stored when an electric field causes the electron and nucleus spins to snap into opposite states, one up and the other down, or vice versa.

These qubits would have a few benefits, say the researchers: Theyd have very low error rates, for example. Qubits are fragile things, so any real-world quantum computer must still work regardless of whether some of its qubits fall apart, and errors should be as infrequent as possible. These qubits are also built into silicon and controlled by electric fields, meaning they could potentially be integrated into silicon chips. The qubits can interact with one another over large distances, which leaves room for other non-quantum pieces of the quantum computer. But the authors point out that some challenges do exist, including the handling of noise and phonons (tiny vibrations).

This is just one of several ideas researchers have for qubits. Companies are already plowing ahead building quantum computersyou may have heard of the controversial D-Wave computer with two thousand qubits (this is far less powerful than scientists would want, and theres debate over whether it can outperform any classical computers). The D-Wave relies on superconductors to create its qubits, materials with no electronic resistance that show quantum mechanical effects on macroscopic scales. There are also existing ion traps, where atoms on some surface are trapped by electric fields, and optics solutions where qubit information gets stored on light particles or photons.

As far as this latest idea goes, its potentially a big advance, Na Young Kim, Associate Professor at the University of Waterloos Institute for Quantum Computing told Gizmodo in an email. At the moment, ion traps and superconducting systems seem to stand in the front line, but there are big hurdles to overcome. Silicon systems may have a great potential to scale up if a robust design is solidified, and translated to present silicon technologies, she said. In that sense, this work certainly pushes silicon systems closer to the next phase of quantum computing development.

Its important to stay realistic with all of this though. Martin LaForest, senior manager of scientific outreach also at the Institute for Quantum Computing at the University of Waterloo recently told me that were now at the junction where physical quantum computer blueprints are beginning to meet theoretical demand required to reap quantum computings benefits. But were still a ways off from a computer that scientists actually use. Chris Wilson (again from the IQC) recently told me that a quantum computer that works the way you think when you hear computer would require possibly a hundred thousand physical qubits. Youre talking about a machine that looks like a modern supercomputer, something that fills a warehouse, he said.

Ultimately, this latest advance is a blueprint for what could potentially be some important quantum computer hardware. Even still, dont expect to see a quantum computer in your office any time soon (you know, unless you work at IBM or Google).

[Nature Communications]

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Quantum computer a possibility in 10 years – News.com.au – NEWS.com.au

It looks like a prop from Doctor Who or Hollywood’s idea of a mad professor’s crazy invention.

But the glittering lump of steel sprouting foil-wrapped pipes balanced on a stack of books and magazines represents a revolution in computing that could change the world.

The 60cm tall machine housed in a cramped laboratory at the University of Sussex is a prototype ion qubit quantum computer.

Still a work in progress, it is designed to demonstrate technology that marks a leap forward in attempts to build unimaginably powerful computers based on the weird principles of quantum physics.

Scientists hope that in as little as 10 years they will be able to scale up the device to produce the first commercially available universal quantum computer capable of solving myriad different problems.

Quantum computers are the ultimate multi-taskers, carrying out many operations at once to work millions of times faster than conventional computers.

They could theoretically unravel incredibly complex problems in days that would take a modern supercomputer billions of years to solve, and transform fields such as finance, drug discovery, biochemistry, materials science and encryption.

A conventional computer stores “bits” of information as binary code sequences of zeroes and ones, but a quantum computer “qubit” can be a zero, a one, both a zero and a one, or an infinite number of values in between.

That is due to the strange ability of subatomic particles to be in more than one state at the same time, until they are observed or interfered with. Only then does one or other value materialise. In a similar way, a spinning coin hides its identity until a hand stops it to reveal a face that is heads or tails.

Speaking at the British Science Festival in Brighton, Professor Winfried Hensinger, who heads the university’s quantum technology lab, says even Albert Einstein was “freaked out” by quantum effects and called them “spooky”.

Then 10 to 20 years ago physicists started asked themselves whether it might be possible to build a quantum device that could perform certain computations “unbelievably fast”.

“What does unbelievably fast mean?” said Hensinger “Unbelievably fast means that it could calculate something that even the fastest supercomputer in the world would take billions of years to calculate in minutes, days or weeks.

“It means quantum computers can solve problems you couldn’t even dream about solving before.”

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