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  • richardmitnick 11:47 am on August 17, 2018 Permalink | Reply
    Tags: , NSF STAQ project, Quantum Computing   

    From HPC Wire: “STAQ(ing) the Quantum Computing Deck” 

    From HPC Wire

    August 16, 2018
    John Russell

    1
    No image caption or credit

    Quantum computers – at least for now – remain noisy. That’s another way of saying unreliable and in diverse ways that often depend on the specific quantum technology used. One idea is to mitigate noisiness and perhaps seamlessly capture some of the underlying quantum physics by mapping quantum algorithms more directly to the underlying hardware; this might make nearer-term quantum computers practical for some problems. This approach, at least in part, is central to the Software Tailored Architecture for Quantum Design (STAQ) project, announced by NSF last week and led by co-PIs Kenneth Brown and Jungsang Kim of Duke University.

    Every project needs a goal and the big callout here is building a 64- (or more) qubit ion trap-based quantum computer capable of tackling problems that classical computers currently stumble on. But that doesn’t catch the scope of the project which is making a point of leveraging multidiscipline expertise to put co-design to work in the quantum domain, exploring specific algorithms for condensed matter physics and quantum chemistry, as well as more general quantum algorithm optimization. There’s also a requirement to run a summer school to share the learnings.

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    No image caption or credit

    “I always joke that if I knew what the silicon transistor was of quantum computing, I would just do it. But I don’t.” Brown told HPCwire. “Right now I think both superconductors and ion traps have shown a lot of progress and demonstrated a large number of algorithms. The advantage of trapped ions is that every ion is the same. For these small chains [of ions in the trap] you do get this advantage of basically being able to achieve communication between any pair. In superconducting devices, typically, you are only able to talk to sort of neighbor qubits. So if you have an algorithm which requires a longer distance communication between qubits, there is some cost you have to pay to get the information from one to the other.”

    There’s a lot going on here – as there is throughout the quantum computing research community. Zeroing in on ion traps for quantum computing isn’t new but it hasn’t received the same notice that semiconductor-based superconducting approaches have á la IBM, Google, D-Wave, Rigetti et. al. NIST (National Institute of Standards and Technology) has put ion trap technology for use as super accurate atomic clocks and a few academic groups have also explored ion trap quantum computing, but without the fanfare attendant other efforts. It turns out ion trap technology – somewhat similar to the mass spec we all know – has several strengths for use in quantum computing.

    Brown, Kim, and colleague Christopher Monroe’s (University of Maryland) have written a nice paper on the topic, Co-Designing a Scalable Quantum Computer with Trapped Atomic Ions. Brown is quick to point out 1,000-qubit scale-up ideas presented in the 2016 paper far exceed STAQ’s goal, but that such scaling ambitions do seem reachable over time with ion trap technology.

    Here’s brief excerpt from their paper touching on ion technology’s attraction:

    “Superconducting circuitry exploits the significant advantages of modern lithography and fabrication technologies: it can be integrated on a solid-state platform and many qubits can simply be printed on a chip. However, they suffer from inhomogeneities and decoherence, as no two superconducting qubits are the same, and their connectivity cannot be reconfigured without replacing the chip or modifying the wires connecting them within a very low temperature environment.

    “Trapped atomic ions, on the other hand, feature virtually identical qubits, and their wiring can be reconfigured by modifying externally applied electromagnetic fields. However, atomic qubit switching speeds are generally much slower than solid state devices, and the development of engineering infrastructure for trapped ion quantum computers and the mitigation of noise and decoherence from the applied control fields is just beginning.”

    Perhaps a quick (and imperfect) description of ion trap technology is warranted. It’s similar to mass spec. Ions are loaded into traps by generating neutral atoms of the desired element and ionizing the atoms once in the trapping volume. Electrodes (rods) are used to generate forces to contain the ions. RF and LASER emissions are used to control the ions, which can be lined in ‘stationary’ chains. Individual ions have their electron states manipulating using LASERs which turns them into qubit registers. Brown’s group is using Ytterbium (Yb+) ions whose outer electron shell structure is well-suited for manipulation.

    “The trap we use looks like a computer chip, sort of like metal on silicon chip. It’s similar to the four-rod trap (quadrupole) you probably know from mass spec. You cut one of the rods and then you’ve unfolded the trap onto a plate and advantage of that is it allows you to then move the ions around, break the break chains apart, and that sort of thing. It also gives you more control over fields that are containing the ions and the direction of the chain itself. That is housed in a vacuum chamber which is achieved with either vacuum system or with a cryogenic chamber. This is one of the designs questions we are working on right, deciding which way to go,” said Brown.

    One important ion trap technology advantage, according to Brown, is the qubit type, something called ‘hyperfine’ qubits. “They basically have no memory error. So unlike many other qubits where you have a constant decay – and it’s all relative to the gate speeds – our relative decay-to-gate-speed is a long, long time. For example, the best result I know of is if you have a microsecond gate time, which is kind of typical for ions, you can have a memory time of ten minutes,” he said.

    As explained in their paper, “Qubits stored in trapped atomic ions are represented by two stable electronic levels within each ion, often represented as an effective spin with the two states |↓⟩and |↑⟩corresponding to bit values 0 and 1. The qubits can be initialized and detected with nearly perfect accuracy using conventional optical pumping and state-dependent fluorescence techniques. This restricts the atomic species of trapped ion qubits to those with simple electronic structure (e.g., those with a single valence electron: Be+, Mg+, Ca+, Sr+, Ba+, Zn+, Hg+, Cd+, and Yb+)” Shown below is a schematic from their paper roughly describing a chip-based ion trap.

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    Co-design is the central tenet for STAQ. “This idea of the software tailored architecture, co-design, is basically we want to make the tools which optimize the mapping of the ideal mathematical algorithm to the actual device of interest. So there are a few things we plan to leverage. One is the at the bottom layer. We often abstract the physics of the quantum device. This has actually been really useful for quantum information as a whole. It allows people to talk about superconducting machines, or ion trap machines, or photon computers, so all these things using the same language. But the underlying physics beneath that gate layer [are] different and there might be some opportunities to simplify some algorithms such that we actually don’t completely remove that abstraction and allow some of the physics [specific to ion trap technology] to seep up to the programmer,” noted Brown.

    Building a stack able to take advantage of this flexibility is one of STAQ’s goals. “The idea of the stack is to try to actually do what one of my colleagues says is like a crossword puzzle. We just don’t optimize the algorithm, and then optimize the gate set, and then optimize each gate on the hardware, but we try to modify the gates so that it’s the most appropriate for optimizing the algorithm given the problem,” said Brown.

    The breadth of expertise on the STAQ team, said Brown, is a distinct advantage: “We have computer architects. We have quantum information theorists. We have people more on the applications side, and hardware people. You need all those people. You need those different layers working. I think what’s nice is we are reaching a point where these machines are reaching sufficient sophistication that it is easier to find people to think about architecture.”

    In some sense flexibility in manipulating ion chains (breaking apart at different lengths, remote entanglement among qubits) allows an almost FPGA-programming-like quality to ion trap quantum computing. “You can do these two-qubit gates between any pair [of ions] and the reason is it’s not like a direct interaction with its neighbor but an interaction which is mediated by the collective motion of the ion chain. In terms of actually mapping algorithms to computers it’s quite nice because if I think about the connection between qubits it’s like a fully connected graph,” said Brown.

    “Now that’s not going to scale to 1000 qubits but it’s not clear not what the limit is. We know 10 qubits, 20 qubits is no problem. [And] we have some ideas on how to get to 50 qubits but at some point we are going to have to shift the way we put these things together.”

    Quantum chemistry is one area of application being examined. “The challenge in doing quantum chemistry on a normal conventional computer is there’s a mismatch between how much classical data we need to store a quantum state,” said Brown. “With a quantum computer you already have this win where there’s a better match. The quantum state on the computer representing the molecule uses a comparable amount of space because they are both in some sense quantum memory. The next thing is each system has kind of its own natural interaction. With an ion trap system, the way the particular gate is performed, the underlying interaction looks a lot looks a lot like a magnetic interaction between two systems. So if the problem you are trying to solve maps nicely to this kind of magnetic interaction, there are actually a lot of shortcuts you can take.”

    Given ion trap technology’s flexibility, STAQ hopes to learn whether it may be possible or worthwhile to create application-specific architectures.

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    “That is one of our big research questions,” according to Brown. “[The issue] is what is the gain there. If you think about a tablet computer or an iPad, it has a facial recognition chip. Its job is just to see faces, right. So we expect that quantum computers will be kind of like that, at least in near term, sort of an extra processor that is interacting with some classical computer. It may turn out to be possible to make quantum processors that are say specifically designed for quantum chemistry problems, that could be a great accelerator for all kinds of applications in chemistry.”

    While STAQ plans to leverage the underlying characteristics ion trap technology which might include ASIC-like capabilities, “all of the devices we plan to make will be universal in that they will allow you to do universal quantum computing,” emphasized Brown.

    STAQ will also run an annual summer school at Duke aimed at two different audiences, said Brown, one drawn from upper level undergraduate and early graduate school students looking to learn more about quantum information and another group drawn from industry.

    Looking at near-term (~18-month) goals, Brown said, “On the algorithm side I hope to identify target algorithms for a computer on the scale of say 60 to 70 qubits. On the experimental side, that first year and a half will be building a new engineering design and building a new system based on our previous experiments with ion traps but moving more towards a functional computer and [something] less like a physics experiment.”

    See the full article here .


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  • richardmitnick 8:03 am on August 8, 2018 Permalink | Reply
    Tags: , , Quantum Computing   

    From National Science Foundation: “NSF launches effort to create first practical quantum computer” 

    From National Science Foundation

    8.7.18

    Joshua Chamot, NSF
    703-292-4489
    jchamot@nsf.gov

    Ken Kingery, Duke University
    (919) 660-8414
    ken.kingery@duke.edu

    $15 million grant will support multi-institution quantum research collaboration.

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    A fabricated trap that researchers use to capture and control atomic ion qubits (quantum bits). Credit: K. Hudek, Ion Q&E / E. Edwards, JQI

    From codebreaking to aircraft design, complex problems in a wide range of fields exist that even today’s best computers cannot solve.

    To accelerate the development of a practical quantum computer that will one day answer currently unsolvable research questions, the National Science Foundation (NSF) has awarded $15 million over five years to the multi-institution Software-Tailored Architecture for Quantum co-design (STAQ) project.

    “Quantum computers will change everything about the technology we use and how we use it, and we are still taking the initial steps toward realizing this goal,” said NSF Director France Córdova. “Developing the first practical quantum computer would be a major milestone. By bringing together experts who have outlined a path to a practical quantum computer and supporting its development, NSF is working to take the quantum revolution from theory to reality.”

    Today’s quantum computers are mostly proofs of concept, demonstrating the feasibility of certain principles. While they have grown in complexity as researchers’ ability to control and construct quantum systems has improved, they have not yet solved a computational problem for which the answer was unknown.

    The project’s integrated approach to developing a practical quantum computer relies on finding new algorithms based on optimization and scientific computing problems, improving quantum computer hardware, and developing software tools that optimize algorithm performance for the specific machine in development.

    STAQ emerged from an NSF Ideas Lab, one of a series of week-long, free-form exchanges among researchers from a wide range of fields that aim to generate creative, collaborative proposals to address a given research challenge. This particular NSF Ideas Lab focused on the Practical Fully-Connected Quantum Computer challenge. STAQ will involve physicists, computer scientists and engineers from Duke University, the Massachusetts Institute of Technology, Tufts University, University of California-Berkeley, University of Chicago, University of Maryland and University of New Mexico.

    The STAQ researchers will focus on four primary goals:

    Develop a quantum computer with a sufficiently large number of quantum bits (qubits) to solve a challenging calculation.
    Ensure that every qubit interacts with all other qubits in the system, critical for solving fundamental problems in physics.
    Integrate software, algorithms, devices and systems engineering.
    Involve equal input from experimentalists, theorists, engineers and computer scientists.

    “The first truly effective quantum computer will not emerge from one researcher working in a single discipline,” said NSF Chief Operating Officer Fleming Crim. “Quantum computing requires experts from a range of fields, with individuals applying complementary insights to solve some of the most challenging problems in science and engineering. NSF’s STAQ project uniquely addresses that need, providing a cutting-edge approach that promises to dramatically advance U.S. leadership in quantum computing.”

    As a cross-disciplinary project, STAQ encourages convergence across research fields and aligns with The Quantum Leap: Leading the Next Quantum Revolution, one of NSF’s 10 Big Ideas for Future NSF Investments. It is funded through NSF’s Mathematical and Physical Sciences, Engineering, and Computer and Information Science and Engineering directorates.

    About The Quantum Leap: Leading the Next Quantum Revolution

    One of NSF’s 10 Big Ideas, The Quantum Leap initiative aims to accelerate innovative research and provide a path forward for science and engineering to help solve one of the most critical, competitive and challenging issues of our time. Researchers will design, construct and analyze new approaches to quantum computing and test algorithms at a scale beyond the reach of simulations run on classical computers. Quantum research is essential for preparing future scientists and engineers to implement the discoveries of the next quantum revolution into technologies that will benefit the nation.

    See the full article here .


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    The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 “to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense…we are the funding source for approximately 24 percent of all federally supported basic research conducted by America’s colleges and universities. In many fields such as mathematics, computer science and the social sciences, NSF is the major source of federal backing.

     
  • richardmitnick 10:30 am on July 30, 2018 Permalink | Reply
    Tags: , , Hello quantum world, , Quantum Computing,   

    From COSMOS Magazine: “Hello quantum world” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    30 July 2018
    Will Knight

    Quantum computing – IBM

    Inside a small laboratory in lush countryside about 80 kilometres north of New York City, an elaborate tangle of tubes and electronics dangles from the ceiling. This mess of equipment is a computer. Not just any computer, but one on the verge of passing what may, perhaps, go down as one of the most important milestones in the history of the field.

    Quantum computers promise to run calculations far beyond the reach of any conventional supercomputer. They might revolutionise the discovery of new materials by making it possible to simulate the behaviour of matter down to the atomic level. Or they could upend cryptography and security by cracking otherwise invincible codes. There is even hope they will supercharge artificial intelligence by crunching through data more efficiently.

    Yet only now, after decades of gradual progress, are researchers finally close to building quantum computers powerful enough to do things that conventional computers cannot. It’s a landmark somewhat theatrically dubbed ‘quantum supremacy’. Google has been leading the charge toward this milestone, while Intel and Microsoft also have significant quantum efforts. And then there are well-funded startups including Rigetti Computing, IonQ and Quantum Circuits.

    No other contender can match IBM’s pedigree in this area, though. Starting 50 years ago, the company produced advances in materials science that laid the foundations for the computer revolution. Which is why, last October, I found myself at IBM’s Thomas J. Watson Research Center to try to answer these questions: What, if anything, will a quantum computer be good for? And can a practical, reliable one even be built?

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    Credit: Graham Carlow

    Why we think we need a quantum computer

    The research center, located in Yorktown Heights, looks a bit like a flying saucer as imagined in 1961. It was designed by the neo-futurist architect Eero Saarinen and built during IBM’s heyday as a maker of large mainframe business machines. IBM was the world’s largest computer company, and within a decade of the research centre’s construction it had become the world’s fifth-largest company of any kind, just behind Ford and General Electric.

    While the hallways of the building look out onto the countryside, the design is such that none of the offices inside have any windows. It was in one of these cloistered rooms that I met Charles Bennett. Now in his 70s, he has large white sideburns, wears black socks with sandals and even sports a pocket protector with pens in it.

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    Charles Bennett was one of the pioneers who realised quantum computers could solve some problems exponentially faster than conventional computers. Credit:Bartek Sadowski

    Surrounded by old computer monitors, chemistry models and, curiously, a small disco ball, he recalled the birth of quantum computing as if it were yesterday.

    When Bennett joined IBM in 1972, quantum physics was already half a century old, but computing still relied on classical physics and the mathematical theory of information that Claude Shannon had developed at MIT in the 1950s. It was Shannon who defined the quantity of information in terms of the number of ‘bits’ (a term he popularised but did not coin) required to store it. Those bits, the 0s and 1s of binary code, are the basis of all conventional computing.

    A year after arriving at Yorktown Heights, Bennett helped lay the foundation for a quantum information theory that would challenge all that. It relies on exploiting the peculiar behaviour of objects at the atomic scale. At that size, a particle can exist ‘superposed’ in many states (e.g., many different positions) at once. Two particles can also exhibit ‘entanglement’, so that changing the state of one may instantaneously affect the other.

    Bennett and others realised that some kinds of computations that are exponentially time consuming, or even impossible, could be efficiently performed with the help of quantum phenomena. A quantum computer would store information in quantum bits, or qubits. Qubits can exist in superpositions of 1 and 0, and entanglement and a trick called interference can be used to find the solution to a computation over an exponentially large number of states. It’s annoyingly hard to compare quantum and classical computers, but roughly speaking, a quantum computer with just a few hundred qubits would be able to perform more calculations simultaneously than there are atoms in the known universe.

    In the summer of 1981, IBM and MIT organised a landmark event called the First Conference on the Physics of Computation. It took place at Endicott House, a French-style mansion not far from the MIT campus.

    In a photo that Bennett took during the conference, several of the most influential figures from the history of computing and quantum physics can be seen on the lawn, including Konrad Zuse, who developed the first programmable computer, and Richard Feynman, an important contributor to quantum theory. Feynman gave the conference’s keynote speech, in which he raised the idea of computing using quantum effects. “The biggest boost quantum information theory got was from Feynman,” Bennett told me. “He said, ‘Nature is quantum, goddamn it! So if we want to simulate it, we need a quantum computer.’”

    IBM’s quantum computer – one of the most promising in existence – is located just down the hall from Bennett’s office. The machine is designed to create and manipulate the essential element in a quantum computer: the qubits that store information.

    The gap between the dream and the reality

    The IBM machine exploits quantum phenomena that occur in superconducting materials. For instance, sometimes current will flow clockwise and counterclockwise at the same time. IBM’s computer uses superconducting circuits in which two distinct electromagnetic energy states make up a qubit.

    The superconducting approach has key advantages. The hardware can be made using well-established manufacturing methods, and a conventional computer can be used to control the system. The qubits in a superconducting circuit are also easier to manipulate and less delicate than individual photons or ions.

    Inside IBM’s quantum lab, engineers are working on a version of the computer with 50 qubits. You can run a simulation of a simple quantum computer on a normal computer, but at around 50 qubits it becomes nearly impossible.

    That means IBM is theoretically approaching the point where a quantum computer can solve problems a classical computer cannot: in other words, quantum supremacy.

    But as IBM’s researchers will tell you, quantum supremacy is an elusive concept. You would need all 50 qubits to work perfectly, when in reality quantum computers are beset by errors that need to be corrected. It is also devilishly difficult to maintain qubits for any length of time; they tend to ‘decohere’, or lose their delicate quantum nature, much as a smoke ring breaks up at the slightest air current. And the more qubits, the harder both challenges become.

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    The cutting-edge science of quantum computing requires nanoscale precision mixed with the tinkering spirit of home electronics. Researcher Jerry Chow is here shown fitting a circuitboard in the IBM quantum research lab. Jon Simon

    “If you had 50 or 100 qubits and they really worked well enough, and were fully error-corrected – you could do unfathomable calculations that can’t be replicated on any classical machine, now or ever,” says Robert Schoelkopf, a Yale professor and founder of a company called Quantum Circuits. “The flip side to quantum computing is that there are exponential ways for it to go wrong.”

    Another reason for caution is that it isn’t obvious how useful even a perfectly functioning quantum computer would be. It doesn’t simply speed up any task you throw at it; in fact, for many calculations, it would actually be slower than classical machines. Only a handful of algorithms have so far been devised where a quantum computer would clearly have an edge. And even for those, that edge might be short-lived. The most famous quantum algorithm, developed by Peter Shor at MIT, is for finding the prime factors of an integer. Many common cryptographic schemes rely on the fact that this is hard for a conventional computer to do. But cryptography could adapt, creating new kinds of codes that don’t rely on factorisation.

    This is why, even as they near the 50-qubit milestone, IBM’s own researchers are keen to dispel the hype around it. At a table in the hallway that looks out onto the lush lawn outside, I encountered Jay Gambetta, a tall, easygoing Australian who researches quantum algorithms and potential applications for IBM’s hardware. “We’re at this unique stage,” he said, choosing his words with care. “We have this device that is more complicated than you can simulate on a classical computer, but it’s not yet controllable to the precision that you could do the algorithms you know how to do.”

    What gives the IBMers hope is that even an imperfect quantum computer might still be a useful one.

    Gambetta and other researchers have zeroed in on an application that Feynman envisioned back in 1981. Chemical reactions and the properties of materials are determined by the interactions between atoms and molecules. Those interactions are governed by quantum phenomena. A quantum computer can – at least in theory – model those in a way a conventional one cannot.

    Last year, Gambetta and colleagues at IBM used a seven-qubit machine to simulate the precise structure of beryllium hydride. At just three atoms, it is the most complex molecule ever modelled with a quantum system. Ultimately, researchers might use quantum computers to design more efficient solar cells, more effective drugs or catalysts that turn sunlight into clean fuels.

    Those goals are a long way off. But, Gambetta says, it may be possible to get valuable results from an error-prone quantum machine paired with a classical computer.

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    Credit Cosmos Magazine

    Physicist’s dream to engineer’s nightmare

    “The thing driving the hype is the realisation that quantum computing is actually real,” says Isaac Chuang, a lean, soft-spoken MIT professor. “It is no longer a physicist’s dream – it is an engineer’s nightmare.”

    Chuang led the development of some of the earliest quantum computers, working at IBM in Almaden, California, during the late 1990s and early 2000s. Though he is no longer working on them, he thinks we are at the beginning of something very big – that quantum computing will eventually even play a role in artificial intelligence.

    But he also suspects that the revolution will not really begin until a new generation of students and hackers get to play with practical machines. Quantum computers require not just different programming languages but a fundamentally different way of thinking about what programming is. As Gambetta puts it: “We don’t really know what the equivalent of ‘Hello, world’ is on a quantum computer.”

    We are beginning to find out. In 2016 IBM connected a small quantum computer to the cloud. Using a programming tool kit called QISKit, you can run simple programs on it; thousands of people, from academic researchers to schoolkids, have built QISKit programs that run basic quantum algorithms. Now Google and other companies are also putting their nascent quantum computers online. You can’t do much with them, but at least they give people outside the leading labs a taste of what may be coming.

    The startup community is also getting excited. A short while after seeing IBM’s quantum computer, I went to the University of Toronto’s business school to sit in on a pitch competition for quantum startups. Teams of entrepreneurs nervously got up and presented their ideas to a group of professors and investors. One company hoped to use quantum computers to model the financial markets. Another planned to have them design new proteins. Yet another wanted to build more advanced AI systems. What went unacknowledged in the room was that each team was proposing a business built on a technology so revolutionary that it barely exists. Few seemed daunted by that fact.

    This enthusiasm could sour if the first quantum computers are slow to find a practical use. The best guess from those who truly know the difficulties –people like Bennett and Chuang – is that the first useful machines are still several years away. And that’s assuming the problem of managing and manipulating a large collection of qubits won’t ultimately prove intractable.

    Still, the experts hold out hope. When I asked him what the world might be like when my two-year-old son grows up, Chuang, who learned to use computers by playing with microchips, responded with a grin. “Maybe your kid will have a kit for building a quantum computer,” he said.

    See the full article here .


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  • richardmitnick 10:55 am on July 24, 2018 Permalink | Reply
    Tags: , Daniel Bowring at FNAL, , , , Quantum Computing, ,   

    From Fermilab: “Daniel Bowring receives $2.5 million from DOE to search for axions with quantum sensors” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermilab , an enduring source of strength for the US contribution to scientific research world wide.

    July 19, 2018
    Jordan Rice

    1
    Daniel Bowring examines a superconducting qubit mounted in a copper microwave cavity. Photo: Reidar Hahn

    Dark matter makes up nearly 80 percent of all matter in the universe, yet its nature has eluded scientists.

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al


    Caterpillar Project A Milky-Way-size dark-matter halo and its subhalos circled, an enormous suite of simulations . Griffen et al. 2016

    Scientists theorize that it could take the form of a subatomic particle, and one possible candidate comes in the form of a small, theoretical particle called the axion. If it exists, the axion will interact incredibly weakly with matter, so detecting one requires an incredibly sensitive detector.

    Fermilab scientist Daniel Bowring is planning to build just such an instrument. The Department of Energy has selected Bowring for a 2018 Early Career Research Award to build a detector that would ferret out the hypothesized particle. He will receive $2.5 million over five years to build and operate his experiment. The award funds equipment, engineers, technicians and a postdoctoral researcher.

    “We are very motivated to find the axion because it would solve several interesting problems for us in the particle physics community,” Bowring said.

    Not only would the axion’s discovery explain, at least in part, the nature of dark matter, it could also solve the strong CP problem, a long-standing thorn in the side of theoretical physics models.

    The strong CP problem is an inconsistency in particle physics. Particles behave differently from their mirror-reversed, antimatter counterparts — at least, they do under the influence of the electromagnetic force and the weak nuclear force (which governs nuclear decay).

    But under the influence of the strong force (which holds matter together), particles and their mirror-image antiparticles behave similarly. Or, in physics speak, they’re CP-symmetric under the strong force. (CP stands for charge-parity. It’s the property that’s flipped when you take a mirror image of a particle’s antimatter partner.) Why is the strong force the exception?

    One potential answer lies in the existence of the axion. In the math of strong interactions, the addition of the axion enables theoretical models to reflect the reality of strong-force CP symmetry.

    Bowring is following the axion math where it leads — to the construction of a device that can pick up the signal of the fundamental particle, whose mass is predicted to be vanishingly small, between 1 billion and 1 trillion times smaller than an electron.

    One way to look for the axion is to look for light: In the presence of a strong electromagnetic field — Bowring’s experiment will use about 14 Tesla, or roughly 10 times stronger than an MRI magnet — an axion should convert into a single particle of light, called a photon, which is more easily observed.

    “Physicists have gotten pretty good at detecting photons over the years,” Bowring said.

    When an axion enters the detector filled with the electromagnetic field, the particle will spontaneously convert into a photon with a specific frequency. The frequency corresponds to the axion’s mass, so scientists can measure the axion mass indirectly, thanks to the detection of particles of light.

    Much like someone tuning a sensitive AM radio, researchers will scan slowly through the relevant range of photon frequencies until they pick up a signal, which would point to the presence of an axion.

    It’s a subtle business, one that requires being able to detect single photons. While photon detection is an old hat for physicists, discerning a lone photon amid the experimental noise of a particle detector is a job for new technology. Bowring’s experiment will use supersensitive, superconducting quantum bits, or qubits, to pluck the solo photon signal from the noise and thus accurately count the number of detected photons.

    Bowring’s experiment will be an opportunity to bridge the gap between particle physics and the science behind quantum computing.

    Quantum computing – IBM

    “Daniel’s proposed experiment will demonstrate how qubits, the essential elements of quantum computing, can be used to detect a range of axion masses,” said Fermilab scientist Keith Gollwitzer. “Quantum computing may be the next large step in computing power and particle physics experiments.”

    In that respect, the application of technologies in their infancy to century-old problems is a reflection of the larger scientific field.

    “Fermilab’s mission is doing particle physics, and qubits are just a way for us to meet the requirements of that mission,” Bowring says. “It is a way for us to build new experiments that address the problems of particle physics at the forefront of where the field is.”

    See the full article here .


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    FNAL Icon

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.


    FNAL/MINERvA

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

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    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL Minos Far Detector

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    FNAL ICARUS

    FNAL Holometer

     
  • richardmitnick 8:02 am on July 24, 2018 Permalink | Reply
    Tags: , , , , Quantum Computing,   

    From JHU HUB: “Evidence revealed for a new property of quantum matter” 

    Johns Hopkins

    From JHU HUB

    June 12, 2018 [Where has this been? Just popped into JHU email.]

    A theorized but never-before detected property of quantum matter has now been spotted in the lab, a team led by a Johns Hopkins scientist reports.

    The study findings, published online in the journal Science, show that a particular quantum material first synthesized 20 years ago, called k-(BEDT-TTF)2Hg(SCN)2 Br, behaves like a metal but is derived from organic compounds. The material can demonstrate electrical dipole fluctuations—irregular oscillations of tiny charged poles on the material—even in extremely cold conditions, in the neighborhood of minus 450 degrees Fahrenheit.

    “What we found with this particular quantum material is that, even at super-cold temperatures, electrical dipoles are still present and fluctuate according to the laws of quantum mechanics,” said Natalia Drichko, associate research professor in physics at Johns Hopkins University and the study’s senior author.

    2
    Natalia Drichko in her lab. Image credit: Jon Schroeder

    “Usually we think of quantum mechanics as a theory of small things, like atoms, but here we observe that the whole crystal is behaving quantum-mechanically.”

    Classical physics describes most of the behavior of physical objects we see and experience in everyday life. In classical physics, objects freeze at extremely low temperatures, Drichko said. In quantum physics—science that primarily describes the behavior of matter and energy at the atomic level and smaller—there is motion even at those frigid temperatures, Drichko said.

    “That’s one of the major differences between classical and quantum physics that condensed matter physicists are exploring,” she said.

    An electrical dipole is a pair of equal but oppositely charged poles separated by some distance. Such dipoles can, for instance, allow a hair to “stick” to a comb through the exchange of static electricity: Tiny dipoles form on the edge of the comb and the edge of the hair.

    2
    The structure of the crystal that was studied in the research; an individual molecule is highlighted in red. Image credit: Institute for Quantum Matter/JHU

    Drichko’s research team observed the new extreme-low-temperature electrical state of the quantum matter in Drichko’s Raman spectroscopy lab, where the key work was done by graduate student Nora Hassan. Team members focused light on a small crystal of the material. Employing techniques from other disciplines, including chemistry and biology, they found proof of the dipole fluctuations.

    The study was possible because of the team’s home-built, custom-engineered spectrometer, which increased the sensitivity of the measurements 100 times.

    The unique quantum effect the team found could potentially be used in quantum computing, a type of computing in which information is captured and stored in ways that take advantage of the quantum states of matter.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    About the Hub

    We’ve been doing some thinking — quite a bit, actually — about all the things that go on at Johns Hopkins. Discovering the glue that holds the universe together, for example. Or unraveling the mysteries of Alzheimer’s disease. Or studying butterflies in flight to fine-tune the construction of aerial surveillance robots. Heady stuff, and a lot of it.

    In fact, Johns Hopkins does so much, in so many places, that it’s hard to wrap your brain around it all. It’s too big, too disparate, too far-flung.

    We created the Hub to be the news center for all this diverse, decentralized activity, a place where you can see what’s new, what’s important, what Johns Hopkins is up to that’s worth sharing. It’s where smart people (like you) can learn about all the smart stuff going on here.

    At the Hub, you might read about cutting-edge cancer research or deep-trench diving vehicles or bionic arms. About the psychology of hoarders or the delicate work of restoring ancient manuscripts or the mad motor-skills brilliance of a guy who can solve a Rubik’s Cube in under eight seconds.

    There’s no telling what you’ll find here because there’s no way of knowing what Johns Hopkins will do next. But when it happens, this is where you’ll find it.

    Johns Hopkins Campus

    The Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

    The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

    What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

     
  • richardmitnick 11:25 am on July 17, 2018 Permalink | Reply
    Tags: , Quantum Computing,   

    From University of New South Wales: “Tuning in to quantum: scientists unlock signal frequency control of precision atom qubits” 

    U NSW bloc

    From University of New South Wales

    16 Jul 2018

    Australian scientists have achieved a new milestone in their approach to creating a quantum computer chip in silicon, demonstrating the ability to tune the control frequency of a qubit by engineering its atomic configuration.

    1
    The frequency spectrum of an engineered molecule. The three peaks represent three different configurations of spins within the atomic nuclei, and the distance between the peaks depends on the exact distance between atoms forming the molecule. Photo: Dr Sam Hile

    Australian scientists have achieved a new milestone in their approach to creating a quantum computer chip in silicon, demonstrating the ability to tune the control frequency of a qubit by engineering its atomic configuration. The work has been published in Science Advances.

    A team of researchers from the Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) at UNSW Sydney have successfully implemented an atomic engineering strategy for individually addressing closely spaced spin qubits in silicon.

    The researchers built two qubits – one an engineered molecule consisting of two phosphorus atoms with a single electron, and the other a single phosphorus atom with a single electron – and placed them just 16 nanometres apart in a silicon chip.

    By patterning a microwave antenna above the qubits with precision alignment, the qubits were exposed to frequencies of around 40GHz. The results showed that when changing the frequency of the signal used to control the electron spin, the single atom had a dramatically different control frequency compared to the electron spin in the molecule of two phosphorus atoms.

    The UNSW researchers collaborated closely with experts at Purdue University, who used powerful computational tools to model the atomic interactions and understand how the position of the atoms impacted the control frequencies of each electron even by shifting the atoms by as little as one nanometre.

    “Individually addressing each qubit when they are so close is challenging,” says UNSW Scientia Professor Michelle Simmons, Director CQC2T and co-author of the paper.

    “The research confirms the ability to tune neighbouring qubits into resonance without impacting each other.”

    Creating engineered phosphorus molecules with different separations between the atoms within the molecule allows for families of qubits with different control frequencies. Each molecule can be operated individually by selecting the frequency that controls its electron spin.

    “We can tune into this or that molecule – a bit like tuning in to different radio stations,” says Sam Hile, lead co-author of the paper and Research Fellow at UNSW.

    “It creates a built-in address which will provide significant benefits for building a silicon quantum computer.”

    Tuning in and individually controlling qubits within a 2 qubit system is a precursor to demonstrating the entangled states that are necessary for a quantum computer to function and carry out complex calculations.

    These results show how the team – led by Professor Simmons – have further built on their unique Australian approach of creating quantum bits from precisely positioned individual atoms in silicon.

    By engineering the atomic placement of the atoms within the qubits in the silicon chip, the molecules can be created with different resonance frequencies. This means that controlling the spin of one qubit will not affect the spin of the neighbouring qubit, leading to fewer errors – an essential requirement for the development of a full-scale quantum computer.

    “The ability to engineer the number of atoms within the qubits provides a way of selectively addressing one qubit from another, resulting in lower error rates even though they are so closely spaced,” says Professor Simmons.

    “These results highlight the ongoing advantages of atomic qubits in silicon.”

    This latest advance in spin control follows from the team’s recent research into controllable interactions between two qubits.

    2
    Dr Sam Hile, lead co-author of the paper, working on the dilution refrigerator in which the qubit device operates. Photo: CQC2T

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U NSW Campus

    Welcome to UNSW Australia (The University of New South Wales), one of Australia’s leading research and teaching universities. At UNSW, we take pride in the broad range and high quality of our teaching programs. Our teaching gains strength and currency from our research activities, strong industry links and our international nature; UNSW has a strong regional and global engagement.

    In developing new ideas and promoting lasting knowledge we are creating an academic environment where outstanding students and scholars from around the world can be inspired to excel in their programs of study and research. Partnerships with both local and global communities allow UNSW to share knowledge, debate and research outcomes. UNSW’s public events include concert performances, open days and public forums on issues such as the environment, healthcare and global politics. We encourage you to explore the UNSW website so you can find out more about what we do.

     
  • richardmitnick 7:21 pm on July 5, 2018 Permalink | Reply
    Tags: Able to process 10 billion photonic qubits every second, , Photons have added appeal because they can swiftly shuttle information over long distances and they are compatible with fabricated chips, Quantum Computing, , , Semiconductor quantum transistor opens the door for photon-based computing   

    From Joint Quantum Institute: “Semiconductor quantum transistor opens the door for photon-based computing” 

    JQI bloc

    From Joint Quantum Institute

    1
    Researchers demonstrate the first single-photon transistor using a semiconductor chip. They used a single photon, stored in a quantum memory, to toggle the state of other photons. (Credit: E. Edwards/JQI)

    Transistors are tiny switches that form the bedrock of modern computing—billions of them route electrical signals around inside a smartphone, for instance.

    Quantum computers will need analogous hardware to manipulate quantum information. But the design constraints for this new technology are stringent, and today’s most advanced processors can’t be repurposed as quantum devices. That’s because quantum information carriers, dubbed qubits, have to follow different rules laid out by quantum physics.

    Scientists can use many kinds of quantum particles as qubits, even the photons that make up light. Photons have added appeal because they can swiftly shuttle information over long distances and they are compatible with fabricated chips. However, making a quantum transistor triggered by light has been challenging because it requires that the photons interact with each other, something that doesn’t ordinarily happen on its own.

    Now, researchers at the Joint Quantum Institute (JQI), led by JQI Fellow Edo Waks have cleared this hurdle and demonstrated the first single-photon transistor using a semiconductor chip. The device, described in the July 6 issue of Science , is compact: Roughly one million of these new transistors could fit inside a single grain of salt. It is also fast, able to process 10 billion photonic qubits every second.

    “Using our transistor, we should be able to perform quantum gates between photons,” says Waks. “Software running on a quantum computer would use a series of such operations to attain exponential speedup for certain computational problems.

    The photonic chip is made from a semiconductor with numerous holes in it, making it appear much like a honeycomb. Light entering the chip bounces around and gets trapped by the hole pattern; a small crystal called a quantum dot sits inside the area where the light intensity is strongest. Analogous to conventional computer memory, the dot stores information about photons as they enter the device. The dot can effectively tap into that memory to mediate photon interactions—meaning that the actions of one photon affect others that later arrive at the chip.

    “In a single-photon transistor the quantum dot memory must persist long enough to interact with each photonic qubit,” says Shuo Sun, the lead author of the new work who is a Postdoctoral Research Fellow at Stanford University*. “This allows a single photon to switch a bigger stream of photons, which is essential for our device to be considered a transistor.”

    To test that the chip operated like a transistor, the researchers examined how the device responded to weak light pulses that usually contained only one photon. In a normal environment, such dim light might barely register. However, in this device, a single photon gets trapped for a long time, registering its presence in the nearby dot.

    The team observed that a single photon could, by interacting with the dot, control the transmission of a second light pulse through the device. The first light pulse acts like a key, opening the door for the second photon to enter the chip. If the first pulse didn’t contain any photons, the dot blocked subsequent photons from getting through. This behavior is similar to a conventional transistor where a small voltage controls the passage of current through it’s terminals. Here, the researchers successfully replaced the voltage with a single photon and demonstrated that their quantum transistor could switch a light pulse containing around 30 photons before the quantum dot’s memory ran out.

    Waks, who is also a professor in the University of Maryland Department of Electrical and Computer Engineering, says that his team had to test different aspects of the device’s performance prior to getting the transistor to work. “Until now, we had the individual components necessary to make a single photon transistor, but here we combined all of the steps into a single chip,” Waks says.

    Sun says that with realistic engineering improvements their approach could allow many quantum light transistors to be linked together. The team hopes that such speedy, highly connected devices will eventually lead to compact quantum computers that process large numbers of photonic qubits.

    *Other contributors and affiliations

    Edo Waks has affiliations with the University of Maryland Department of Electrical and Computer Engineering (ECE), Department of Physics, Joint Quantum Institute, and the Institute for Research in Electronics and Applied Physics (IREAP).
    Shuo Sun was a UMD graduate student at the time of this research. He is now a postdoctoral research fellow at Stanford University.
    JQI Fellow Glenn Solomon, a physicist at the National Institute of Standards and Technology, grew the sample used in this research.
    Hyochul Kim was a postdoctoral research at UMD at the time of the research. He is now at Samsung Advanced Institute of Technology.
    Zhouchen Luo is currently a UMD ECE graduate student.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    We are on the verge of a new technological revolution as the strange and unique properties of quantum physics become relevant and exploitable in the context of information science and technology.

    The Joint Quantum Institute (JQI) is pursuing that goal through the work of leading quantum scientists from the Department of Physics of the University of Maryland (UMD), the National Institute of Standards and Technology (NIST) and the Laboratory for Physical Sciences (LPS). Each institution brings to JQI major experimental and theoretical research programs that are dedicated to the goals of controlling and exploiting quantum systems.

     
  • richardmitnick 8:24 pm on June 13, 2018 Permalink | Reply
    Tags: , , Exascale supercomputing still to come, , NQI- Congress's National Quantum Initiative, , Quantum Computing,   

    From Science Magazine: “Quantum physics gets attention—and brighter funding prospects—in Congress” 

    AAAS
    From Science Magazine

    Jun. 13, 2018
    Gabriel Popkin

    1
    Ions trapped between gold blades serve as information-carrying qubits in a prototype quantum computer.
    E. EDWARDS/JOINT QUANTUM INSTITUTE

    Many members of Congress admit they find quantum physics mind-boggling, with its counterintuitive account of the subatomic world. But that isn’t stopping U.S. lawmakers, as well as policymakers in President Donald Trump’s administration, from backing an emerging effort to better organize and boost funding for quantum research, which could reshape computing, sensors, and communications.

    ORNL IBM AC922 SUMMIT supercomputer just launched by OLCF at ORNL, and there is more to come as we approach exascale supercomputing

    In the coming weeks, the science committee of the House of Representatives is expected to introduce legislation calling for a new, 10-year-long National Quantum Initiative (NQI). The White House, for its part, is scheduled to formally launch a new panel that will guide the federal government’s role in quantum science. Key science agencies are calling on Congress to accelerate spending on quantum research. And the Senate supports a boost for the field: Last week, it approved a mammoth defense policy bill that includes a provision directing the Pentagon to create a new $20 million quantum science program.

    A yearlong push by a coalition of academic researchers and technology firms helped trigger this flurry of activity. Proponents argue the United States needs a better plan for harvesting the potential fruits of quantum research—and for keeping up with global competitors.

    LLNL IBM Sierra ATS2 supercomputer still to come

    Depiction of ANL ALCF Cray Shasta Aurora supercomputer still to come

    The European Union has launched a decadelong quantum research initiative, and China is said to be investing heavily in the field. The United States is “kind of the only major country that’s not doing something [?],” says Chris Monroe, a physicist at the University of Maryland in College Park and co-founder of a startup developing quantum computers, which could outstrip conventional computers on certain problems. [I guess what is depicted below is someone’s idea of nothing.]

    Quantum computing – IBM I

    IBM Quantum Computing

    Last June, a small group of academics, executives, and lobbyists that includes Monroe released a white paper calling for an NQI; they issued a blueprint for the effort in April. Meanwhile, the House science committee held a hearing on the topic last October and plans to release a bill later this month that draws extensively from the blueprint.

    “We must ensure that the United States does not fall behind other nations that are advancing quantum programs,” Science committee chair Lamar Smith (R–TX) said yesterday in a statement about the bill.

    The legislation will authorize the Department of Energy (DOE) and the National Science Foundation (NSF) to create new research centers at universities, federal laboratories, and nonprofit research institutes, according to a committee spokesperson. These research hubs would aim to build alliances between physicists doing fundamental research, engineers who can build devices, and computer scientists developing quantum algorithms. The centers could give academics seeking to develop commercial technologies access to expertise and expensive research tools, says physicist David Awschalom of the University of Chicago in Illinois, one of the blueprint’s authors. “The research needs rapidly outpace any individual lab,” he says.

    The proposal “sounds really promising,” says Danna Freedman, a chemist at Northwestern University in Evanston, Illinois, who did not contribute to the proposal. But Freedman, who synthesizes materials that could be used to build new kinds of quantum computer components, says her enthusiasm “depends to what extent the government decides to prescribe the research.”

    The blueprint recommends that the hubs focus on three areas: developing ultraprecise quantum sensors for biomedicine, navigation, and other applications; hack-proof quantum communication; and quantum computers. The bill will likely leave it up to federal agencies, the new White House quantum panel, and an outside advisory group to determine the initiative’s focus. Backers also say the effort could help advance the development of software for quantum computers—a major hurdle. Right now, just “tens or hundreds of people” can program quantum computers, says William Zeng of Rigetti Computing, a startup in Berkeley, California, seeking to build a quantum computer and offer quantum computing services. “That’s not going to be able to support building the full potential of the tech.”

    It’s not yet known how much funding the House bill, which Republicans on the science panel are crafting, will recommend. The blueprint envisions channeling $800 million over 5 years to the NQI, but even if the bill endorses that figure, congressional appropriators will have the final say. Also uncertain is whether Democrats will sign on and help ensure passage through the full House, and whether the Senate will support the idea.

    In the meantime, lawmakers and the Trump administration are moving to shore up federal spending on quantum science, which analysts in 2016 estimated at about $200 million a year. Adding to the $20 million boost approved by the Senate (but not yet by the entire Congress), Trump’s 2019 budget request would create a new $30 million “Quantum Leap” initiative at NSF and boost DOE’s quantum research programs to $105 million.

    The United States, long seen as a leader, is facing growing global competition in the quantum field, says Walter Copan, director of the National Institutes of Standards and Technology in Gaithersburg, Maryland, which has long played a role in quantum research. “It is the equivalent of a space race now,” says Copan, who met last week with Smith. Focusing federal resources on the field, Copan adds, “has phenomenal promise for the country—if it’s done right.”

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 6:38 pm on June 5, 2018 Permalink | Reply
    Tags: A regular quantum computer — one without non-Abelian anyons — would require error correction, Abelian anyons behave more or less like conventional fermions, , But an even more powerful computational platform would come from what’s known as parafermions which have been theorized but not yet shown to exist. Perhaps their existence could also be proven with , Eliminate error correction which is a major stumbling block in the development of quantum computers, For one useful quantum bit of information you need multiple additional quantum bits to correct errors that arise from random fluctuations in the system, Non-Abelian anyons are for lack of a better way of saying it completely insane. They have very strange properties that could be used in quantum computing or more specifically for what’s known as top, Non-Abelian anyons- quantum quasi-particles that retain a “memory” of their relative positions in the past, Quantum Computing, Quantum Hall liquid, This work suggests that a particular entity known as a Majorana particle is at work in the particular system that we studied. And that suggests that a Majorana-based quantum computer is possible., topological quantum computing — which requires the presence of non-Abelian anyons — is unique in that it doesn’t need error correction to make the quantum bits useful,   

    From Brown University: “New research hints at ‘insane’ particles useful in quantum computing” 

    Brown University
    From Brown University

    June 5, 2018
    Kevin Stacey
    kevin_stacey@brown.edu

    1
    Quantum heat. An image of the experimental setup used to produce evidence of strange quasi-particles called non-Abelian anyons.
    A new measurement of heat conduction in an exotic state of matter points to the presence of strange particles that could be useful in quantum computers.

    In a paper published this week in the journal Nature, a research team including a Brown University physicist has characterized how heat is conducted in a matter state known as a quantum Hall liquid, in which electrons are confined to two dimensions. The findings suggest the presence of non-Abelian anyons, quantum quasi-particles that retain a “memory” of their relative positions in the past. Theorists have suggested that the ability of these particles to retain information could be useful in developing ultra-fast quantum computing systems that don’t require error correction, which is a major stumbling block in the development of quantum computers.

    The research was led by an experimental group at the Weizmann Institute of Science in Rehovot, Israel.

    Weizmann Institute Campus


    Dmitri Feldman, a professor of physics at Brown, was part of the research group. He discussed the findings in an interview.

    Q: Could you explain more about what you and your colleagues found?

    A: We were looking at thermal conductance — which simply means the flow of heat from a higher temperature to a lower temperature — in what’s known as a 5/2 quantum Hall liquid. Quantum Hall liquids are not ‘liquids’ in the conventional sense of the word. The term refers to the behavior of electrons inside certain materials when the electrons become confined in two dimensions in a strong magnetic field.

    What we found was that the quantized heat conductance — meaning a fundamental unit of conductance — in this system is fractional. In other words, the value was not an integer, and that has interesting implications for what’s happening in the system. When the quantum thermal conductance is not an integer, it means that quasi-particles known as non-Abelian anyons are present in this system.

    Q: Can you explain more about non-Abelian anyons?

    A: In the Standard Model of particle physics, there are only two categories of particles: fermions and bosons.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Standard Model of Particle Physics from Symmetry Magazine

    That’s all there is in the world we experience on a daily basis. But in two-dimensional systems like quantum Hall liquids, there can be other types of particles known as anyons. Generally speaking, there are two types of anyons: Abelian anyons and non-Abelian anyons. Abelian anyons behave more or less like conventional fermions, but non-Abelian anyons are, for lack of a better way of saying it, completely insane. They have very strange properties that could be used in quantum computing, or more specifically, for what’s known as topological quantum memory.

    Q: What’s the connection between non-Abelian anyons and quantum computing?

    A: A regular quantum computer — one without non-Abelian anyons — would require error correction. For one useful quantum bit of information, you need multiple additional quantum bits to correct errors that arise from random fluctuations in the system. That’s extremely demanding and a big problem in quantum computing. But topological quantum computing — which requires the presence of non-Abelian anyons — is unique in that it doesn’t need error correction to make the quantum bits useful. That’s because in a non-Abelian system, you can produce states that are completely indistinguishable locally, but globally the states are completely different. So you can have random perturbations of these local quantum numbers, but it won’t change the global quantum numbers, which means the information is safe.

    Q: Where does this line of research go from here?

    A: This work suggests that a particular entity known as a Majorana particle is at work in the particular system that we studied. And that suggests that a Majorana-based quantum computer is possible. But an even more powerful computational platform would come from what’s known as parafermions, which have been theorized but not yet shown to exist. Perhaps their existence could also be proven with similar experimental tools in the future.

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition
    Welcome to Brown

    Brown U Robinson Hall
    Located in historic Providence, Rhode Island and founded in 1764, Brown University is the seventh-oldest college in the United States. Brown is an independent, coeducational Ivy League institution comprising undergraduate and graduate programs, plus the Alpert Medical School, School of Public Health, School of Engineering, and the School of Professional Studies.

    With its talented and motivated student body and accomplished faculty, Brown is a leading research university that maintains a particular commitment to exceptional undergraduate instruction.

    Brown’s vibrant, diverse community consists of 6,000 undergraduates, 2,000 graduate students, 400 medical school students, more than 5,000 summer, visiting and online students, and nearly 700 faculty members. Brown students come from all 50 states and more than 100 countries.

    Undergraduates pursue bachelor’s degrees in more than 70 concentrations, ranging from Egyptology to cognitive neuroscience. Anything’s possible at Brown—the university’s commitment to undergraduate freedom means students must take responsibility as architects of their courses of study.

     
  • richardmitnick 3:46 pm on May 14, 2018 Permalink | Reply
    Tags: Harvard University and MIT, , Institute of Science and Technology Austria, , Quantum Computing, University of Geneva,   

    From University of Leeds via phys.org: “Deeper understanding of quantum chaos may be the key to quantum computers” 

    U Leeds bloc

    From University of Leeds

    phys.org

    May 14, 2018

    1
    Quantum systems can exist in many possible states, here illustrated by groups of spins, each pointing along a certain direction. Thermalization occurs when a system evenly explores all allowed configurations. Instead, when a “quantum scar” forms (as shown in the figure), some configurations emerge as special. This feature allows scarred systems to sustain memory of the initial state despite thermalization. Credit: Zlatko Papic, University of Leeds

    New research gives insight into a recent experiment that was able to manipulate an unprecedented number of atoms through a quantum simulator. This new theory could provide another step on the path to creating the elusive quantum computers.

    1
    Quantum computing – IBM

    An international team of researchers, led by the University of Leeds and in cooperation with the Institute of Science and Technology Austria and the University of Geneva, has provided a theoretical explanation for the particular behaviour of individual atoms that were trapped and manipulated in a recent experiment by Harvard University and MIT [Nature Physics]. The experiment used a system of finely tuned lasers to act as “optical tweezers” to assemble a remarkably long chain of 51 atoms.

    When the quantum dynamics of the atom chain were measured, there were surprising oscillations that persisted for much longer than expected and which couldn’t be explained.

    Study co-author, Dr. Zlatko Papic, Lecturer in Theoretical Physics at Leeds, said: “The previous Harvard-MIT experiment created surprisingly robust oscillations that kept the atoms in a quantum state for an extended time. We found these oscillations to be rather puzzling because they suggested that atoms were somehow able to “remember” their initial configuration while still moving chaotically.

    “Our goal was to understand more generally where such oscillations could come from, since oscillations signify some kind of coherence in a chaotic environment—and this is precisely what we want from a robust quantum computer. Our work suggests that these oscillations are due to a new physical phenomenon that we called ‘quantum many-body scar’.”

    In everyday life, particles will bounce off one another until they explore the entire space, settling eventually into a state of equilibrium. This process is called thermalisation. A quantum scar is when a special configuration or pathway leaves an imprint on the particles’ state that keeps them from filling the entire space. This prevents the systems from reaching thermalisation and allows them to maintain some quantum effects.

    Dr. Papic said: “We are learning that quantum dynamics can be much more complex and intricate than simply thermalisation. The practical benefit is that extended periods of oscillations are exactly what is needed if quantum computers are to become a reality. The information processed and stored on these computers will be dependent on keeping the atoms in more than one state at any time, it is a constant battle to keep the particles from settling into an equilibrium.”

    Study lead author, Christopher Turner, doctoral researcher at the School of Physics and Astronomy at Leeds, said: “Previous theories involving quantum scars have been formulated for a single particle. Our work has extended these ideas to systems which contain not one but many particles, which are all entangled with each other in complicated ways. Quantum many-body scars might represent a new avenue to realise coherent quantum dynamics.”

    The quantum many-body scars theory sheds light on the quantum states that underpin the strange dynamics of atoms in the Harvard-MIT experiment. Understanding this phenomenon could also pave the way for protecting or extending the lifetime of quantum states in other classes of quantum many-body systems.

    Read more at: https://phys.org/news/2018-05-deeper-quantum-chaos-key.html#jCp

    See the full article here.

    Please help promote STEM in your local schools.

    stem

    Stem Education Coalition

    U Leeds Campus

    The University, established in 1904, is one of the largest higher education institutions in the UK. We are a world top 100 university and are renowned globally for the quality of our teaching and research. The strength of our academic expertise combined with the breadth of disciplines we cover, provides a wealth of opportunities and has real impact on the world in cultural, economic and societal ways. The University strives to achieve academic excellence within an ethical framework informed by our values of integrity, equality and inclusion, community and professionalism.

     
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