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  • richardmitnick 8:59 am on July 30, 2019 Permalink | Reply
    Tags: A team of physicists at University of Illinois at Chicago and the University of Hamburg have taken a different approach., Entangled Majorana quasiparticles produced by splitting an electron into two halves are surprisingly stable., , , Majorana quasiparticles, , , Quantum superposition, Qubits, , , They remember how they've been moved around a property that could be exploited for storing information., They've started with a rhenium superconductor a material that conducts electricity with zero resistance when supercooled to around 6 Kelvin (–267°C; 449°F)., , U Hamburg,   

    From University of Illinois and U Hamburg, via Science Alert: “An Elusive Particle That Acts as Its Own Antiparticle Has Just Been Imaged” 

    U Illinois bloc

    From University of Illinois Chicago

    and

    2
    U Hamburg

    via

    30 JULY 2019
    MICHELLE STARR

    3
    (Palacio-Morales et al. Science Advances, 2019)

    New images of the Majorana fermion have brought physicists a step closer to harnessing the mysterious objects for quantum computing.

    These strange objects – particles that acts as their own antiparticles – have a vast as-yet untapped potential to act as qubits, the quantum bits that are the basic units of information in a quantum computer.

    IBM iconic image of Quantum computer

    They’re equivalent to binary bits in a traditional computer. But, where regular bits can represent a 1 or a 0, qubits can be either 1, 0 or both at the same time, a state known as quantum superposition. Quantum superposition is actually pretty hard to maintain, although we’re getting better at it.

    This is where Majorana quasiparticles come in. These are excitations in the collective behaviour of electrons that act like Majorana fermions, and they have a number of properties that make them an attractive candidate for qubits.

    Normally, a particle and an antiparticle will annihilate each other, but entangled Majorana quasiparticles produced by splitting an electron into two halves are surprisingly stable. In addition, they remember how they’ve been moved around, a property that could be exploited for storing information.

    But the quasiparticles have to remain separated by a sufficient distance. This can be done with a special nanowire, but a team of physicists at the University of Illinois at Chicago and the University of Hamburg in Germany have taken a different approach.

    They’ve started with a rhenium superconductor, a material that conducts electricity with zero resistance when supercooled to around 6 Kelvin (–267°C; 449°F).

    On top of these superconductors, the researchers deposited nanoscale islands of single layers of magnetic iron atoms. This creates what is known as a topological superconductor – that is, a superconductor that contains a topological knot.

    “This topological knot is similar to the hole in a donut,” explained physicist Dirk Morr of the University of Illinois at Chicago.

    “You can deform the donut into a coffee mug without losing the hole, but if you want to destroy the hole, you have to do something pretty dramatic, such as eating the donut.”

    When electrons flow through the superconductor, the team predicted that Majorana fermions would appear in a one-dimensional mode at the edges of the iron islands – around the so-called donut hole. And that by using a scanning tunneling microscope – an instrument used for imaging surfaces at the atomic level – they would see this visualised as a bright line.

    Sure enough, a bright line showed up.

    It’s not the first time Majorana fermions have been imaged, but it does represent a step forward. And just last month, a different team of researchers revealed that they had been able to turn Majorana quasiparticles on and off.

    But being able to visualise these particles, the researchers said, brings us closer to using them as qubits.

    “The next step will be to figure out how we can quantum engineer these Majorana qubits on quantum chips and manipulate them to obtain an exponential increase in our computing power,” Morr said.

    The research has been published in Science Advances.

    See the full article here .

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    Please help promote STEM in your local schools.

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    4

    The University

    Universität Hamburg is the largest institution for research and education in northern Germany. As one of the country’s largest universities, we offer a diverse range of degree programs and excellent research opportunities. The University boasts numerous interdisciplinary projects in a broad range of fields and an extensive partner network of leading regional, national, and international higher education and research institutions.
    Sustainable science and scholarship

    Universität Hamburg is committed to sustainability. All our faculties have taken great strides towards sustainability in both research and teaching.
    Excellent research

    As part of the Excellence Strategy of the Federal and State Governments, Universität Hamburg has been granted clusters of excellence for 4 core research areas: Advanced Imaging of Matter (photon and nanosciences), Climate, Climatic Change, and Society (CliCCS) (climate research), Understanding Written Artefacts (manuscript research) and Quantum Universe (mathematics, particle physics, astrophysics, and cosmology).

    An equally important core research area is Infection Research, in which researchers investigate the structure, dynamics, and mechanisms of infection processes to promote the development of new treatment methods and therapies.
    Outstanding variety: over 170 degree programs

    Universität Hamburg offers approximately 170 degree programs within its eight faculties:

    Faculty of Law
    Faculty of Business, Economics and Social Sciences
    Faculty of Medicine
    Faculty of Education
    Faculty of Mathematics, Informatics and Natural Sciences
    Faculty of Psychology and Human Movement Science
    Faculty of Business Administration (Hamburg Business School).

    Universität Hamburg is also home to several museums and collections, such as the Zoological Museum, the Herbarium Hamburgense, the Geological-Paleontological Museum, the Loki Schmidt Garden, and the Hamburg Observatory.
    History

    Universität Hamburg was founded in 1919 by local citizens. Important founding figures include Senator Werner von Melle and the merchant Edmund Siemers. Nobel Prize winners such as the physicists Otto Stern, Wolfgang Pauli, and Isidor Rabi taught and researched at the University. Many other distinguished scholars, such as Ernst Cassirer, Erwin Panofsky, Aby Warburg, William Stern, Agathe Lasch, Magdalene Schoch, Emil Artin, Ralf Dahrendorf, and Carl Friedrich von Weizsäcker, also worked here.
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    U Illinois campus

    The University of Illinois at Urbana-Champaign community of students, scholars, and alumni is changing the world.

    With our land-grant heritage as a foundation, we pioneer innovative research that tackles global problems and expands the human experience. Our transformative learning experiences, in and out of the classroom, are designed to produce alumni who desire to make a significant, societal impact.

    The University of Illinois at Chicago (UIC) is a public research university in Chicago, Illinois. Its campus is in the Near West Side community area, adjacent to the Chicago Loop. The second campus established under the University of Illinois system, UIC is also the largest university in the Chicago area, having approximately 30,000 students[9] enrolled in 15 colleges.

    UIC operates the largest medical school in the United States with research expenditures exceeding $412 million and consistently ranks in the top 50 U.S. institutions for research expenditures.[10][11][12] In the 2019 U.S. News & World Report’s ranking of colleges and universities, UIC ranked as the 129th best in the “national universities” category.[13] The 2015 Times Higher Education World University Rankings ranked UIC as the 18th best in the world among universities less than 50 years old.[14]

    UIC competes in NCAA Division I Horizon League as the UIC Flames in sports. The Credit Union 1 Arena (formerly UIC Pavilion) is the Flames’ venue for home games.

     
  • richardmitnick 8:30 am on July 26, 2019 Permalink | Reply
    Tags: "Stanford physicists count sound particles with quantum microphone", , , Qubits,   

    From Stanford University: “Stanford physicists count sound particles with quantum microphone” 

    Stanford University Name
    From Stanford University

    July 24, 2019
    Ker Than

    A device that eavesdrops on the quantum whispers of atoms could form the basis of a new type of quantum computer.

    1
    Artist’s impression of an array of nanomechanical resonators designed to generate and trap sound particles, or phonons. The mechanical motions of the trapped phonons are sensed by a qubit detector, which shifts its frequency depending on the number of phonons in a resonator. Different phonon numbers are visible as distinct peaks in the qubit spectrum, which are shown schematically behind the resonators. (Image credit: Wentao Jiang)

    Stanford physicists have developed a “quantum microphone” so sensitive that it can measure individual particles of sound, called phonons.

    The device, which is detailed July 24 in the journal Nature, could eventually lead to smaller, more efficient quantum computers that operate by manipulating sound rather than light.

    “We expect this device to allow new types of quantum sensors, transducers and storage devices for future quantum machines,” said study leader Amir Safavi-Naeini, an assistant professor of applied physics at Stanford’s School of Humanities and Sciences.

    Quantum of motion

    First proposed by Albert Einstein in 1907, phonons are packets of vibrational energy emitted by jittery atoms. These indivisible packets, or quanta, of motion manifest as sound or heat, depending on their frequencies.

    Like photons, which are the quantum carriers of light, phonons are quantized, meaning their vibrational energies are restricted to discrete values – similar to how a staircase is composed of distinct steps.

    “Sound has this granularity that we don’t normally experience,” Safavi-Naeini said. “Sound, at the quantum level, crackles.”

    The energy of a mechanical system can be represented as different “Fock” states – 0, 1, 2, and so on – based on the number of phonons it generates. For example, a “1 Fock state” consist of one phonon of a particular energy, a “2 Fock state” consists of two phonons with the same energy, and so on. Higher phonon states correspond to louder sounds.

    Until now, scientists have been unable to measure phonon states in engineered structures directly because the energy differences between states – in the staircase analogy, the spacing between steps – is vanishingly small. “One phonon corresponds to an energy ten trillion trillion times smaller than the energy required to keep a lightbulb on for one second,” said graduate student Patricio Arrangoiz-Arriola, a co-first author of the study.

    To address this issue, the Stanford team engineered the world’s most sensitive microphone – one that exploits quantum principles to eavesdrop on the whispers of atoms.

    In an ordinary microphone, incoming sound waves jiggle an internal membrane, and this physical displacement is converted into a measurable voltage. This approach doesn’t work for detecting individual phonons because, according to the Heisenberg uncertainty principle, a quantum object’s position can’t be precisely known without changing it.

    “If you tried to measure the number of phonons with a regular microphone, the act of measurement injects energy into the system that masks the very energy that you’re trying to measure,” Safavi-Naeini said.

    Instead, the physicists devised a way to measure Fock states – and thus, the number of phonons – in sound waves directly. “Quantum mechanics tells us that position and momentum can’t be known precisely – but it says no such thing about energy,” Safavi-Naeini said. “Energy can be known with infinite precision.”

    Singing qubits

    The quantum microphone the group developed consists of a series of supercooled nanomechanical resonators, so small that they are visible only through an electron microscope. The resonators are coupled to a superconducting circuit that contains electron pairs that move around without resistance. The circuit forms a quantum bit, or qubit, that can exist in two states at once and has a natural frequency, which can be read electronically. When the mechanical resonators vibrate like a drumhead, they generate phonons in different states.

    “The resonators are formed from periodic structures that act like mirrors for sound. By introducing a defect into these artificial lattices, we can trap the phonons in the middle of the structures,” Arrangoiz-Arriola said.

    Like unruly inmates, the trapped phonons rattle the walls of their prisons, and these mechanical motions are conveyed to the qubit by ultra-thin wires. “The qubit’s sensitivity to displacement is especially strong when the frequencies of the qubit and the resonators are nearly the same,” said joint first-author Alex Wollack, also a graduate student at Stanford.

    However, by detuning the system so that the qubit and the resonators vibrate at very different frequencies, the researchers weakened this mechanical connection and triggered a type of quantum interaction, known as a dispersive interaction, that directly links the qubit to the phonons.

    This bond causes the frequency of the qubit to shift in proportion to the number of phonons in the resonators. By measuring the qubit’s changes in tune, the researchers could determine the quantized energy levels of the vibrating resonators – effectively resolving the phonons themselves.

    “Different phonon energy levels appear as distinct peaks in the qubit spectrum,” Safavi-Naeini said. “These peaks correspond to Fock states of 0, 1, 2 and so on. These multiple peaks had never been seen before.”

    Mechanical quantum mechanical

    Mastering the ability to precisely generate and detect phonons could help pave the way for new kinds of quantum devices that are able to store and retrieve information encoded as particles of sound or that can convert seamlessly between optical and mechanical signals.

    Such devices could conceivably be made more compact and efficient than quantum machines that use photons, since phonons are easier to manipulate and have wavelengths that are thousands of times smaller than light particles.

    “Right now, people are using photons to encode these states. We want to use phonons, which brings with it a lot of advantages,” Safavi-Naeini said. “Our device is an important step toward making a ‘mechanical quantum mechanical’ computer.”

    Other Stanford co-authors include graduate students Zhaoyou Wang, Wentao Jiang, Timothy McKenna and Jeremy Witmer, and postdoctoral researchers Marek Pechal and Raphël Van Laer.

    The research was funded by the David and Lucile Packard Fellowship, the Stanford University Terman Fellowship and the U.S. Office of Naval Research.

    See the full article here .


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    Stanford University campus. No image credit

    Stanford University

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 1:10 pm on March 10, 2019 Permalink | Reply
    Tags: A quantum computer would greatly speed up analysis of the collisions hopefully finding evidence of supersymmetry much sooner—or at least allowing us to ditch the theory and move on., And they’ve been waiting for decades. Google is in the race as are IBM Microsoft Intel and a clutch of startups academic groups and the Chinese government., , At the moment researchers spend weeks and months sifting through the debris from proton-proton collisions in the LCH trying to find exotic heavy sister-particles to all our known particles of matter., “This is a marathon” says David Reilly who leads Microsoft’s quantum lab at the University of Sydney Australia. “And it's only 10 minutes into the marathon.”, , , CERN-Future Circular Collider, For CERN the quantum promise could for instance help its scientists find evidence of supersymmetry or SUSY which so far has proven elusive., , IBM has steadily been boosting the number of qubits on its quantum computers starting with a meagre 5-qubit computer then 16- and 20-qubit machines and just recently showing off its 50-qubit processor, In a bid to make sense of the impending data deluge some at CERN are turning to the emerging field of quantum computing., In a quantum computer each circuit can have one of two values—either one (on) or zero (off) in binary code; the computer turns the voltage in a circuit on or off to make it work., In theory a quantum computer would process all the states a qubit can have at once and with every qubit added to its memory size its computational power should increase exponentially., Last year physicists from the California Institute of Technology in Pasadena and the University of Southern California managed to replicate the discovery of the Higgs boson found at the LHC in 2012, None of the competing teams have come close to reaching even the first milestone., , , Qubits, The quest has now lasted decades and a number of physicists are questioning if the theory behind SUSY is really valid., Traditional computers—be it an Apple Watch or the most powerful supercomputer—rely on tiny silicon transistors that work like on-off switches to encode bits of data., Venture capitalists invested some $250 million in various companies researching quantum computing in 2018 alone.,   

    From WIRED: “Inside the High-Stakes Race to Make Quantum Computers Work” 

    Wired logo

    From WIRED

    03.08.19
    Katia Moskvitch

    1
    View Pictures/Getty Images

    Deep beneath the Franco-Swiss border, the Large Hadron Collider is sleeping.

    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    But it won’t be quiet for long. Over the coming years, the world’s largest particle accelerator will be supercharged, increasing the number of proton collisions per second by a factor of two and a half.

    Once the work is complete in 2026, researchers hope to unlock some of the most fundamental questions in the universe. But with the increased power will come a deluge of data the likes of which high-energy physics has never seen before. And, right now, humanity has no way of knowing what the collider might find.

    To understand the scale of the problem, consider this: When it shut down in December 2018, the LHC generated about 300 gigabytes of data every second, adding up to 25 petabytes (PB) annually. For comparison, you’d have to spend 50,000 years listening to music to go through 25 PB of MP3 songs, while the human brain can store memories equivalent to just 2.5 PB of binary data. To make sense of all that information, the LHC data was pumped out to 170 computing centers in 42 countries [http://greybook.cern.ch/]. It was this global collaboration that helped discover the elusive Higgs boson, part of the Higgs field believed to give mass to elementary particles of matter.

    CERN CMS Higgs Event


    CERN ATLAS Higgs Event

    To process the looming data torrent, scientists at the European Organization for Nuclear Research, or CERN, will need 50 to 100 times more computing power than they have at their disposal today. A proposed Future Circular Collider, four times the size of the LHC and 10 times as powerful, would create an impossibly large quantity of data, at least twice as much as the LHC.

    CERN FCC Future Circular Collider map

    In a bid to make sense of the impending data deluge, some at CERN are turning to the emerging field of quantum computing. Powered by the very laws of nature the LHC is probing, such a machine could potentially crunch the expected volume of data in no time at all. What’s more, it would speak the same language as the LHC. While numerous labs around the world are trying to harness the power of quantum computing, it is the future work at CERN that makes it particularly exciting research. There’s just one problem: Right now, there are only prototypes; nobody knows whether it’s actually possible to build a reliable quantum device.

    Traditional computers—be it an Apple Watch or the most powerful supercomputer—rely on tiny silicon transistors that work like on-off switches to encode bits of data.

    ORNL IBM AC922 SUMMIT supercomputer, No.1 on the TOP500. Credit: Carlos Jones, Oak Ridge National Laboratory/U.S. Dept. of Energy

    Each circuit can have one of two values—either one (on) or zero (off) in binary code; the computer turns the voltage in a circuit on or off to make it work.

    A quantum computer is not limited to this “either/or” way of thinking. Its memory is made up of quantum bits, or qubits—tiny particles of matter like atoms or electrons. And qubits can do “both/and,” meaning that they can be in a superposition of all possible combinations of zeros and ones; they can be all of those states simultaneously.

    For CERN, the quantum promise could, for instance, help its scientists find evidence of supersymmetry, or SUSY, which so far has proven elusive.

    Standard Model of Supersymmetry via DESY

    At the moment, researchers spend weeks and months sifting through the debris from proton-proton collisions in the LCH, trying to find exotic, heavy sister-particles to all our known particles of matter. The quest has now lasted decades, and a number of physicists are questioning if the theory behind SUSY is really valid. A quantum computer would greatly speed up analysis of the collisions, hopefully finding evidence of supersymmetry much sooner—or at least allowing us to ditch the theory and move on.

    A quantum device might also help scientists understand the evolution of the early universe, the first few minutes after the Big Bang. Physicists are pretty confident that back then, our universe was nothing but a strange soup of subatomic particles called quarks and gluons. To understand how this quark-gluon plasma has evolved into the universe we have today, researchers simulate the conditions of the infant universe and then test their models at the LHC, with multiple collisions. Performing a simulation on a quantum computer, governed by the same laws that govern the very particles that the LHC is smashing together, could lead to a much more accurate model to test.

    Beyond pure science, banks, pharmaceutical companies, and governments are also waiting to get their hands on computing power that could be tens or even hundreds of times greater than that of any traditional computer.

    And they’ve been waiting for decades. Google is in the race, as are IBM, Microsoft, Intel and a clutch of startups, academic groups, and the Chinese government. The stakes are incredibly high. Last October, the European Union pledged to give $1 billion to over 5,000 European quantum technology researchers over the next decade, while venture capitalists invested some $250 million in various companies researching quantum computing in 2018 alone. “This is a marathon,” says David Reilly, who leads Microsoft’s quantum lab at the University of Sydney, Australia. “And it’s only 10 minutes into the marathon.”

    Despite the hype surrounding quantum computing and the media frenzy triggered by every announcement of a new qubit record, none of the competing teams have come close to reaching even the first milestone, fancily called quantum supremacy—the moment when a quantum computer performs at least one specific task better than a standard computer. Any kind of task, even if it is totally artificial and pointless. There are plenty of rumors in the quantum community that Google may be close, although if true, it would give the company bragging rights at best, says Michael Biercuk, a physicist at the University of Sydney and founder of quantum startup Q-CTRL. “It would be a bit of a gimmick—an artificial goal,” says Reilly “It’s like concocting some mathematical problem that really doesn’t have an obvious impact on the world just to say that a quantum computer can solve it.”

    That’s because the first real checkpoint in this race is much further away. Called quantum advantage, it would see a quantum computer outperform normal computers on a truly useful task. (Some researchers use the terms quantum supremacy and quantum advantage interchangeably.) And then there is the finish line, the creation of a universal quantum computer. The hope is that it would deliver a computational nirvana with the ability to perform a broad range of incredibly complex tasks. At stake is the design of new molecules for life-saving drugs, helping banks to adjust the riskiness of their investment portfolios, a way to break all current cryptography and develop new, stronger systems, and for scientists at CERN, a way to glimpse the universe as it was just moments after the Big Bang.

    Slowly but surely, work is already underway. Federico Carminati, a physicist at CERN, admits that today’s quantum computers wouldn’t give researchers anything more than classical machines, but, undeterred, he’s started tinkering with IBM’s prototype quantum device via the cloud while waiting for the technology to mature. It’s the latest baby step in the quantum marathon. The deal between CERN and IBM was struck in November last year at an industry workshop organized by the research organization.

    Set up to exchange ideas and discuss potential collab­orations, the event had CERN’s spacious auditorium packed to the brim with researchers from Google, IBM, Intel, D-Wave, Rigetti, and Microsoft. Google detailed its tests of Bristlecone, a 72-qubit machine. Rigetti was touting its work on a 128-qubit system. Intel showed that it was in close pursuit with 49 qubits. For IBM, physicist Ivano Tavernelli took to the stage to explain the company’s progress.

    IBM has steadily been boosting the number of qubits on its quantum computers, starting with a meagre 5-qubit computer, then 16- and 20-qubit machines, and just recently showing off its 50-qubit processor.

    IBM iconic image of Quantum computer

    Carminati listened to Tavernelli, intrigued, and during a much needed coffee break approached him for a chat. A few minutes later, CERN had added a quantum computer to its impressive technology arsenal. CERN researchers are now starting to develop entirely new algorithms and computing models, aiming to grow together with the device. “A fundamental part of this process is to build a solid relationship with the technology providers,” says Carminati. “These are our first steps in quantum computing, but even if we are coming relatively late into the game, we are bringing unique expertise in many fields. We are experts in quantum mechanics, which is at the base of quantum computing.”

    The attraction of quantum devices is obvious. Take standard computers. The prediction by former Intel CEO Gordon Moore in 1965 that the number of components in an integrated circuit would double roughly every two years has held true for more than half a century. But many believe that Moore’s law is about to hit the limits of physics. Since the 1980s, however, researchers have been pondering an alternative. The idea was popularized by Richard Feynman, an American physicist at Caltech in Pasadena. During a lecture in 1981, he lamented that computers could not really simulate what was happening at a subatomic level, with tricky particles like electrons and photons that behave like waves but also dare to exist in two states at once, a phenomenon known as quantum superposition.

    Feynman proposed to build a machine that could. “I’m not happy with all the analyses that go with just the classical theory, because nature isn’t classical, dammit,” he told the audience back in 1981. “And if you want to make a simulation of nature, you’d better make it quantum mechanical, and by golly it’s a wonderful problem, because it doesn’t look so easy.”

    And so the quantum race began. Qubits can be made in different ways, but the rule is that two qubits can be both in state A, both in state B, one in state A and one in state B, or vice versa, so there are four probabilities in total. And you won’t know what state a qubit is at until you measure it and the qubit is yanked out of its quantum world of probabilities into our mundane physical reality.

    In theory, a quantum computer would process all the states a qubit can have at once, and with every qubit added to its memory size, its computational power should increase exponentially. So, for three qubits, there are eight states to work with simultaneously, for four, 16; for 10, 1,024; and for 20, a whopping 1,048,576 states. You don’t need a lot of qubits to quickly surpass the memory banks of the world’s most powerful modern supercomputers—meaning that for specific tasks, a quantum computer could find a solution much faster than any regular computer ever would. Add to this another crucial concept of quantum mechanics: entanglement. It means that qubits can be linked into a single quantum system, where operating on one affects the rest of the system. This way, the computer can harness the processing power of both simultaneously, massively increasing its computational ability.

    While a number of companies and labs are competing in the quantum marathon, many are running their own races, taking different approaches. One device has even been used by a team of researchers to analyze CERN data, albeit not at CERN. Last year, physicists from the California Institute of Technology in Pasadena and the University of Southern California managed to replicate the discovery of the Higgs boson, found at the LHC in 2012, by sifting through the collider’s troves of data using a quantum computer manufactured by D-Wave, a Canadian firm based in Burnaby, British Columbia. The findings didn’t arrive any quicker than on a traditional computer, but, crucially, the research showed a quantum machine could do the work.

    One of the oldest runners in the quantum race, D-Wave announced back in 2007 that it had built a fully functioning, commercially available 16-qubit quantum computer prototype—a claim that’s controversial to this day. D-Wave focuses on a technology called quantum annealing, based on the natural tendency of real-world quantum systems to find low-energy states (a bit like a spinning top that inevitably will fall over). A D-Wave quantum computer imagines the possible solutions of a problem as a landscape of peaks and valleys; each coordinate represents a possible solution and its elevation represents its energy. Annealing allows you to set up the problem, and then let the system fall into the answer—in about 20 milliseconds. As it does so, it can tunnel through the peaks as it searches for the lowest valleys. It finds the lowest point in the vast landscape of solutions, which corresponds to the best possible outcome—although it does not attempt to fully correct for any errors, inevitable in quantum computation. D-Wave is now working on a prototype of a universal annealing quantum computer, says Alan Baratz, the company’s chief product officer.

    Apart from D-Wave’s quantum annealing, there are three other main approaches to try and bend the quantum world to our whim: integrated circuits, topological qubits and ions trapped with lasers. CERN is placing high hopes on the first method but is closely watching other efforts too.

    IBM, whose computer Carminati has just started using, as well as Google and Intel, all make quantum chips with integrated circuits—quantum gates—that are superconducting, a state when certain metals conduct electricity with zero resistance. Each quantum gate holds a pair of very fragile qubits. Any noise will disrupt them and introduce errors—and in the quantum world, noise is anything from temperature fluctuations to electromagnetic and sound waves to physical vibrations.

    To isolate the chip from the outside world as much as possible and get the circuits to exhibit quantum mechanical effects, it needs to be supercooled to extremely low temperatures. At the IBM quantum lab in Zurich, the chip is housed in a white tank—a cryostat—suspended from the ceiling. The temperature inside the tank is a steady 10 millikelvin or –273 degrees Celsius, a fraction above absolute zero and colder than outer space. But even this isn’t enough.

    Just working with the quantum chip, when scientists manipulate the qubits, causes noise. “The outside world is continually interacting with our quantum hardware, damaging the information we are trying to process,” says physicist John Preskill at the California Institute of Technology, who in 2012 coined the term quantum supremacy. It’s impossible to get rid of the noise completely, so researchers are trying to suppress it as much as possible, hence the ultracold temperatures to achieve at least some stability and allow more time for quantum computations.

    “My job is to extend the lifetime of qubits, and we’ve got four of them to play with,” says Matthias Mergenthaler, an Oxford University postdoc student working at IBM’s Zurich lab. That doesn’t sound like a lot, but, he explains, it’s not so much the number of qubits that counts but their quality, meaning qubits with as low a noise level as possible, to ensure they last as long as possible in superposition and allow the machine to compute. And it’s here, in the fiddly world of noise reduction, that quantum computing hits up against one of its biggest challenges. Right now, the device you’re reading this on probably performs at a level similar to that of a quantum computer with 30 noisy qubits. But if you can reduce the noise, then the quantum computer is many times more powerful.

    Once the noise is reduced, researchers try to correct any remaining errors with the help of special error-correcting algorithms, run on a classical computer. The problem is, such error correction works qubit by qubit, so the more qubits there are, the more errors the system has to cope with. Say a computer makes an error once every 1,000 computational steps; it doesn’t sound like much, but after 1,000 or so operations, the program will output incorrect results. To be able to achieve meaningful computations and surpass standard computers, a quantum machine has to have about 1,000 qubits that are relatively low noise and with error rates as corrected as possible. When you put them all together, these 1,000 qubits will make up what researchers call a logical qubit. None yet exist—so far, the best that prototype quantum devices have achieved is error correction for up to 10 qubits. That’s why these prototypes are called noisy intermediate-scale quantum computers (NISQ), a term also coined by Preskill in 2017.

    For Carminati, it’s clear the technology isn’t ready yet. But that isn’t really an issue. At CERN the challenge is to be ready to unlock the power of quantum computers when and if the hardware becomes available. “One exciting possibility will be to perform very, very accurate simulations of quantum systems with a quantum computer—which in itself is a quantum system,” he says. “Other groundbreaking opportunities will come from the blend of quantum computing and artificial intelligence to analyze big data, a very ambitious proposition at the moment, but central to our needs.”

    But some physicists think NISQ machines will stay just that—noisy—forever. Gil Kalai, a professor at Yale University, says that error correcting and noise suppression will never be good enough to allow any kind of useful quantum computation. And it’s not even due to technology, he says, but to the fundamentals of quantum mechanics. Interacting systems have a tendency for errors to be connected, or correlated, he says, meaning errors will affect many qubits simultaneously. Because of that, it simply won’t be possible to create error-correcting codes that keep noise levels low enough for a quantum computer with the required large number of qubits.

    “My analysis shows that noisy quantum computers with a few dozen qubits deliver such primitive computational power that it will simply not be possible to use them as the building blocks we need to build quantum computers on a wider scale,” he says. Among scientists, such skepticism is hotly debated. The blogs of Kalai and fellow quantum skeptics are forums for lively discussion, as was a recent much-shared article titled “The Case Against Quantum Computing”—followed by its rebuttal, “The Case Against the Case Against Quantum Computing.

    For now, the quantum critics are in a minority. “Provided the qubits we can already correct keep their form and size as we scale, we should be okay,” says Ray Laflamme, a physicist at the University of Waterloo in Ontario, Canada. The crucial thing to watch out for right now is not whether scientists can reach 50, 72, or 128 qubits, but whether scaling quantum computers to this size significantly increases the overall rate of error.

    3
    The Quantum Nano Centre in Canada is one of numerous big-budget research and development labs focussed on quantum computing. James Brittain/Getty Images

    Others believe that the best way to suppress noise and create logical qubits is by making qubits in a different way. At Microsoft, researchers are developing topological qubits—although its array of quantum labs around the world has yet to create a single one. If it succeeds, these qubits would be much more stable than those made with integrated circuits. Microsoft’s idea is to split a particle—for example an electron—in two, creating Majorana fermion quasi-particles. They were theorized back in 1937, and in 2012 researchers at Delft University of Technology in the Netherlands, working at Microsoft’s condensed matter physics lab, obtained the first experimental evidence of their existence.

    “You will only need one of our qubits for every 1,000 of the other qubits on the market today,” says Chetan Nayak, general manager of quantum hardware at Microsoft. In other words, every single topological qubit would be a logical one from the start. Reilly believes that researching these elusive qubits is worth the effort, despite years with little progress, because if one is created, scaling such a device to thousands of logical qubits would be much easier than with a NISQ machine. “It will be extremely important for us to try out our code and algorithms on different quantum simulators and hardware solutions,” says Carminati. “Sure, no machine is ready for prime time quantum production, but neither are we.”

    Another company Carminati is watching closely is IonQ, a US startup that spun out of the University of Maryland. It uses the third main approach to quantum computing: trapping ions. They are naturally quantum, having superposition effects right from the start and at room temperature, meaning that they don’t have to be supercooled like the integrated circuits of NISQ machines. Each ion is a singular qubit, and researchers trap them with special tiny silicon ion traps and then use lasers to run algorithms by varying the times and intensities at which each tiny laser beam hits the qubits. The beams encode data to the ions and read it out from them by getting each ion to change its electronic states.

    In December, IonQ unveiled its commercial device, capable of hosting 160 ion qubits and performing simple quantum operations on a string of 79 qubits. Still, right now, ion qubits are just as noisy as those made by Google, IBM, and Intel, and neither IonQ nor any other labs around the world experimenting with ions have achieved quantum supremacy.

    As the noise and hype surrounding quantum computers rumbles on, at CERN, the clock is ticking. The collider will wake up in just five years, ever mightier, and all that data will have to be analyzed. A non-noisy, error-corrected quantum computer will then come in quite handy.

    See the full article here .

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  • richardmitnick 11:49 am on March 1, 2019 Permalink | Reply
    Tags: "Yale researchers create a ‘universal entangler’ for new quantum tech", Potential uses in quantum computing and cryptography and quantum communications, , Qubits, The entangling mechanism is called an exponential-SWAP gate,   

    From Yale University: “Yale researchers create a ‘universal entangler’ for new quantum tech” 

    Yale University bloc

    From Yale University

    February 27, 2019
    Jim Shelton

    One of the key concepts in quantum physics is entanglement, in which two or more quantum systems become so inextricably linked that their collective state can’t be determined by observing each element individually. Now Yale researchers have developed a “universal entangler” that can link a variety of encoded particles on demand.

    The discovery represents a powerful new mechanism with potential uses in quantum computing, cryptography, and quantum communications. The research is led by the Yale laboratory of Robert Schoelkopf and appears in the journal Nature.

    Quantum calculations are accomplished with delicate bits of data called qubits, which are prone to errors. To implement faithful quantum computation, scientists say, they need “logical” qubits whose errors can be detected and rectified using quantum error correction codes.

    “We’ve shown a new way of creating gates between logically-encoded qubits that can eventually be error-corrected,” said Schoelkopf, the Sterling Professor of Applied Physics and Physics at Yale and director of the Yale Quantum Institute. “It’s a much more sophisticated operation than what has been performed previously.”

    The entangling mechanism is called an exponential-SWAP gate. In the study, researchers demonstrated the new technology by deterministically entangling encoded states in any chosen configurations or codes, each housed in two otherwise isolated, 3D superconducting microwave cavities.

    1
    Yale researchers have created a way to entangle a variety of encoded particles on demand.

    “This universal entangler is critical for robust quantum computation,” said Yvonne Gao, co-first author of the study. “Scientists have invented a wealth of hardware-efficient, quantum error correction codes — each one cleverly designed with unique characteristics that can be exploited for different applications. However, each of them requires wiring up a new set of tailored operations, introducing a significant hardware overhead and reduced versatility.”

    The universal entangler mitigates this limitation by providing a gate between any desired input states. “We can now choose any desired codes or even change them on the fly without having to re-wire the operation,” said co-first author Brian Lester.

    The discovery is just the latest step in Yale’s quantum research work. Yale scientists are at the forefront of efforts to develop the first fully useful quantum computers and have done pioneering work in quantum computing with superconducting circuits.

    Additional authors of the study are Kevin Chou, Luigi Frunzio, Michel Devoret, Liang Jiang, and Steven Girvin. The research was supported by the U.S. Army Research Office.

    See the full article here .

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    Yale University Campus

    Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

     
  • richardmitnick 10:22 am on February 23, 2019 Permalink | Reply
    Tags: , , , , , Qubits, Semiconductor quantum dots,   

    From University of Cambridge: “Physicists get thousands of semiconductor nuclei to do ‘quantum dances’ in unison” 

    U Cambridge bloc

    From University of Cambridge

    22 Feb 2019
    Communications office

    1
    Theoretical ESR spectrum buildup as a function of two-photon detuning δ and drive time τ, for a Rabi frequency of Ω = 3.3 MHz on the central transition. Credit: University of Cambridge.

    A team of Cambridge researchers have found a way to control the sea of nuclei in semiconductor quantum dots so they can operate as a quantum memory device.

    Quantum dots are crystals made up of thousands of atoms, and each of these atoms interacts magnetically with the trapped electron. If left alone to its own devices, this interaction of the electron with the nuclear spins, limits the usefulness of the electron as a quantum bit – a qubit.

    Led by Professor Mete Atatüre from Cambridge’s Cavendish Laboratory, the researchers are exploiting the laws of quantum physics and optics to investigate computing, sensing or communication applications.

    “Quantum dots offer an ideal interface, as mediated by light, to a system where the dynamics of individual interacting spins could be controlled and exploited,” said Atatüre, who is a Fellow of St John’s College. “Because the nuclei randomly ‘steal’ information from the electron they have traditionally been an annoyance, but we have shown we can harness them as a resource.”

    The Cambridge team found a way to exploit the interaction between the electron and the thousands of nuclei using lasers to ‘cool’ the nuclei to less than 1 milliKelvin, or a thousandth of a degree above the absolute zero temperature. They then showed they can control and manipulate the thousands of nuclei as if they form a single body in unison, like a second qubit. This proves the nuclei in the quantum dot can exchange information with the electron qubit and can be used to store quantum information as a memory device. The results are reported in the journal Science.

    Quantum computing aims to harness fundamental concepts of quantum physics, such as entanglement and superposition principle, to outperform current approaches to computing and could revolutionise technology, business and research. Just like classical computers, quantum computers need a processor, memory, and a bus to transport the information backwards and forwards. The processor is a qubit which can be an electron trapped in a quantum dot, the bus is a single photon that these quantum dots generate and are ideal for exchanging information. But the missing link for quantum dots is quantum memory.

    Atatüre said: “Instead of talking to individual nuclear spins, we worked on accessing collective spin waves by lasers. This is like a stadium where you don’t need to worry about who raises their hands in the Mexican wave going round, as long as there is one collective wave because they all dance in unison.

    “We then went on to show that these spin waves have quantum coherence. This was the missing piece of the jigsaw and we now have everything needed to build a dedicated quantum memory for every qubit.”

    In quantum technologies, the photon, the qubit and the memory need to interact with each other in a controlled way. This is mostly realised by interfacing different physical systems to form a single hybrid unit which can be inefficient. The researchers have been able to show that in quantum dots, the memory element is automatically there with every single qubit.

    Dr Dorian Gangloff, one of the first authors of the paper [Science] and a Fellow at St John’s, said the discovery will renew interest in these types of semiconductor quantum dots. Dr Gangloff explained: “This is a Holy Grail breakthrough for quantum dot research – both for quantum memory and fundamental research; we now have the tools to study dynamics of complex systems in the spirit of quantum simulation.”

    The long term opportunities of this work could be seen in the field of quantum computing. Last month, IBM launched the world’s first commercial quantum computer, and the Chief Executive of Microsoft has said quantum computing has the potential to ‘radically reshape the world’.

    Gangloff said: “The impact of the qubit could be half a century away but the power of disruptive technology is that it is hard to conceive of the problems we might open up – you can try to think of it as known unknowns but at some point you get into new territory. We don’t yet know the kind of problems it will help to solve which is very exciting.”

    See the full article here .

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 2:32 pm on October 5, 2018 Permalink | Reply
    Tags: , DOE Ofice of HIgh Energy Physics, , ORNL researchers advance quantum computing science through six DOE awards, , Qubits   

    From Oak Ridge National Laboratory: “ORNL researchers advance quantum computing, science through six DOE awards” 

    i1

    From Oak Ridge National Laboratory

    October 3, 2018
    Scott Jones, Communications
    jonesg@ornl.gov
    865.241.6491

    1
    Oak Ridge National Laboratory will be working on new projects aimed at accelerating quantum information science. Credit: Andy Sproles/Oak Ridge National Laboratory, U.S. Dept. of Energy.

    2
    ORNL researchers will leverage various microscopy platforms for quantum computing projects. Credit: Genevieve Martin/Oak Ridge National Laboratory, U.S. Dept. of Energy.

    The Department of Energy’s Oak Ridge National Laboratory is the recipient of six awards from DOE’s Office of Science aimed at accelerating quantum information science (QIS), a burgeoning field of research increasingly seen as vital to scientific innovation and national security.

    The awards, which were made in conjunction with the White House Summit on Advancing American Leadership in QIS, will leverage and strengthen ORNL’s established programs in quantum information processing and quantum computing.

    The application of quantum mechanics to computing and the processing of information has enormous potential for innovation across the scientific spectrum. Quantum technologies use units known as qubits to greatly increase the threshold at which information can be transmitted and processed. Whereas traditional “bits” have a value of either 0 or 1, qubits are encoded with values of both 0 and 1, or any combination thereof, at the same time, allowing for a vast number of possibilities for storing data.

    While in its infancy, the technology is being harnessed to develop computers that, when mature, will be exponentially more powerful than today’s leading systems. Beyond computing, however, quantum information science shows great promise to advance a vast array of research domains, from encryption to artificial intelligence to cosmology.

    The ORNL awards represent three Office of Science programs.

    “Software Stack and Algorithms for Automating Quantum-Classical Computing,” a new project supported by the Office of Advanced Scientific Computing Research, will develop methods for programming quantum computers. Led by ORNL’s Pavel Lougovski, the team of researchers from ORNL, Johns Hopkins University Applied Physics Lab, University of Southern California, University of Maryland, Georgetown University, and Microsoft, will tackle translating scientific applications into functional quantum programs that return accurate results when executed on real-world faulty quantum hardware. The team will develop an open-source algorithm and software stack that will automate the process of designing, executing, and analyzing the results of quantum algorithms, thus enabling new discovery across many scientific domains with an emphasis on applications in quantum field theory, nuclear physics, condensed matter, and quantum machine learning.

    ORNL’s Christopher M. Rouleau will lead the “Thin Film Platform for Rapid Prototyping Novel Materials with Entangled States for Quantum Information Science” project, funded by Basic Energy Sciences. The project aims to establish an agile AI-guided synthesis platform coupling reactive pulsed laser deposition with quick decision-making diagnostics to enable the rapid exploration of a wide spectrum of candidate thin-film materials for QIS; understand the dynamics of photonic states by combining a novel cathodoluminescence scanning electron microscopy platform with ultrafast laser spectroscopy; and enable understanding of entangled spin states for topological quantum computing by developing a novel scanning tunneling microscopy platform.

    ORNL’s Stephen Jesse will lead the “Understanding and Controlling Entangled and Correlated Quantum States in Confined Solid-State Systems Created via Atomic Scale Manipulation,” a new project supported by Basic Energy Sciences that includes collaborators from Harvard and MIT. The goal of the project is to use advanced electron microscopes to engineer novel materials on an atom-by-atom basis for use in QIS. These microscopes, along with other powerful instrumentation, will also be used to assess emerging quantum properties in-situ to aid the assembly process. Collaborators from Harvard will provide theoretical and computational effort to design quantum properties on demand using ORNL’s high-performance computing resources.

    ORNL is also partnering with Pacific Northwest National Laboratory, Berkeley Laboratory, and the University of Michigan on a project funded by the Office of Basic Energy Sciences titled “Embedding Quantum Computing into Many-Body Frameworks for Strongly-Correlated Molecular and Materials Systems.” The research team will develop methods for solving problems in computational chemistry for highly correlated electronic states. ORNL’s contribution, led by Travis Humble, will support this collaboration by translating applications of computational chemistry into the language needed for running on quantum computers and testing these ideas on experimental hardware.

    ORNL will support multiple projects awarded by the Office of High Energy Physics to develop methods for detecting high-energy particles using quantum information science. They include:

    “Quantum-Enhanced Detection of Dark Matter and Neutrinos,” in collaboration with the University of Wisconsin, Tufts, and San Diego State University. This project will use quantum simulation to calculate detector responses to dark matter particles and neutrinos. A new simulation technique under development will require extensive work in error mitigation strategies to correctly evaluate scattering cross sections and other physical quantities. ORNL’s effort, led by Raphael Pooser, will help develop these simulation techniques and error mitigation strategies for the new quantum simulator device, thus ensuring successful detector calculations.

    “Particle Track Pattern Recognition via Content Addressable Memory and Adiabatic Quantum Optimization: OLYMPUS Experiment Revisited,” a collaboration with John Hopkins Applied Physics Laboratory aimed at identifying rare events found in the data generated by experiments at particle colliders. ORNL principal investigator Travis Humble will apply new ideas for data analysis using experimental quantum computers that target faster response times and greater memory capacity for tracking signatures of high-energy particles.

    “HEP ML and Optimization Go Quantum,” in collaboration with Fermi National Accelerator Laboratory and Lockheed Martin Corporation, which will investigate how quantum machine learning methods may be applied to solving key challenges in optimization and data analysis. Advances in training machine learning networks using quantum computer promise greater accuracy and faster response times for data analysis. ORNL principal investigators Travis Humble and Alex McCaskey will help to develop these new methods for quantum machine learning for existing quantum computers by using the XACC programming tools, which offer a flexible framework by which to integrate quantum computing into scientific software.

    See the full article here .


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    ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.

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  • richardmitnick 11:27 am on September 27, 2018 Permalink | Reply
    Tags: , Atom-based quantum computer, , , , , Qubits, Rubidium atoms, Rydberg state,   

    From Science Magazine: “Arrays of atoms emerge as dark horse candidate to power quantum computers” 

    AAAS
    From Science Magazine

    Sep. 26, 2018
    Sophia Chen

    1
    Lasers are used to trap arrays of atoms within glass chambers made by ColdQuanta, a neutral atom quantum computing startup.
    COLDQUANTA INC.

    In a small basement laboratory, Harry Levine, a Harvard University graduate student in physics, can assemble a rudimentary computer in a fraction of a second. There isn’t a processor chip in sight; his computer is powered by 51 rubidium atoms that reside in a glass cell the size of a matchbox. To create his computer, he lines up the atoms in single file, using a laser split into 51 beams. More lasers—six beams per atom—slow the atoms until they are nearly motionless. Then, with yet another set of lasers, he coaxes the atoms to interact with each other, and, in principle, perform calculations.

    It’s a quantum computer, which manipulates “qubits” that can encode zeroes and ones simultaneously in what’s called a superposition state. If scaled up, it might vastly outperform conventional computers at certain tasks. But in the world of quantum computing, Levine’s device is somewhat unusual. In the race to build a practical quantum device, investment has largely gone to qubits that can be built on silicon, such as tiny circuits of superconducting wire and small semiconductors structures known as quantum dots. Now, two recent studies have demonstrated the promise of the qubits Levine works with: neutral atoms. In one study, a group including Levine showed a quantum logic gate made of two neutral atoms could work with far fewer errors than ever before. And in another, researchers built 3D structures of carefully arranged atoms, showing that more qubits can be packed into a small space by taking advantage of the third dimension.

    The advances, along with the arrival of venture capital funding, suggest neutral atoms could be on the upswing, says Dana Anderson, CEO of ColdQuanta, a Boulder, Colorado–based company that is developing an atom-based quantum computer. “We’ve done our homework,” Anderson says. “This is really in the engineering arena now.”

    Because neutral atoms lack electric charge and interact reluctantly with other atoms, they would seem to make poor qubits. But by using specifically timed laser pulses, physicists can excite an atom’s outermost electron and move it away from the nucleus, inflating the atom to billions of times its usual size. Once in this so-called Rydberg state, the atom behaves more like an ion, interacting electromagnetically with neighboring atoms and preventing them from becoming Rydberg atoms themselves.

    Physicists can exploit that behavior to create entanglement—the quantum state of interdependence needed to perform a computation. If two adjacent atoms are excited into superposition, where both are partially in a Rydberg state and partially in their ground state, a measurement will collapse the atoms to one or the other state. But because only one of the atoms can be in its Rydberg state, the atoms are entangled, with the state of one depending on the state of the other.

    Once entangled, neutral atoms offer some inherent advantages. Atoms need no quality control: They are by definition identical. They’re much smaller than silicon-based qubits, which means, in theory, more qubits can be packed into a small space. The systems operate at room temperature, whereas superconducting qubits need to be placed inside a bulky freezer. And because neutral atoms don’t interact easily, they are more immune to outside noise and can hold onto quantum information for a relatively long time. “Neutral atoms have great potential,” says Mark Saffman, a physicist at the University of Wisconsin in Madison. “From a physics perspective, [they could offer] easier scalability and ultimately better performance.”

    Entangled atoms

    The two new studies bolster these claims. By engineering better quality lasers, Levine and his colleagues, led by physicist Mikhail Lukin at Harvard, were able to accurately program a two-rubidium atom logic gate 97% of the time, they report in a paper published on 20 September in Physical Review Letters. That puts the method closer to the performance of superconducting qubits, which already achieve fidelity rates above 99%. In a second study, published in Nature on 5 September, Antoine Browaeys of the Charles Fabry Laboratory near Paris and his colleagues demonstrated an unprecedented level of control over a 3D array of 72 atoms. To show off their control, they even arranged the atoms into the shape of the Eiffel Tower. Another popular qubit type, ions, are comparably small. But they can’t be stacked this densely because they repel each other, acknowledges Crystal Senko, a physicist at the University of Waterloo in Canada who works on ion quantum computers.

    Not everyone is convinced. Compared with other qubits, neutral atoms tend not to stay put, says Varun Vaidya, a physicist at Xanadu, a quantum computing company in Toronto, Canada, that builds quantum devices with photon qubits. “The biggest issue is just holding onto the atoms,” he says. If an atom falls out of place, Lukin’s automated laser system can reassemble the atoms in less than a second, but Vaidya says this may still prohibit the devices from performing longer tasks. “Right now, nobody knows what’s going to be the best qubit,” Senko says. “The bottom line is, they all have their problems.”

    Still, ColdQuanta has recently received $6.75 million in venture funding. Another startup, Atom Computing, based in Berkeley, California, has raised $5 million. CEO Ben Bloom says the company will pursue qubits made of atoms with two valence electrons instead of rubidium’s one, such as calcium and strontium. Bloom believes these atoms will allow for longer-lived qubits. Lukin says he’s also interested in commercializing his group’s technology.

    The startups, as well as Saffman’s group, are aiming to build fully programmable quantum computers. For now, Lukin wants his group to focus on building quantum simulators, a more limited kind of computer that specializes in solving specific optimization problems by preparing the qubits a certain way and letting them evolve naturally. Levine says his group’s device could, for example, help telecommunications engineers figure out where to put radio towers to minimize cost and maximize coverage. “We’re going to try to do something useful with these devices,” Levine says. “People still don’t know yet what quantum systems can do.”

    In the next year or two, he and his colleagues think neutral atom devices could deliver an answer.

    See the full article here .


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  • richardmitnick 9:25 am on September 27, 2018 Permalink | Reply
    Tags: , Photonic bandgap, , Qubits, Superconducting Metamaterial Traps Quantum Light, Superconducting metamaterials   

    From Caltech: “Superconducting Metamaterial Traps Quantum Light” 

    Caltech Logo

    From Caltech

    09/26/2018

    Robert Perkins
    (626) 395-1862
    rperkins@caltech.edu

    1
    A superconducting metamaterial chip mounted into a microwave test package. The purplish-violet reflection in the center is an optical effect that can seen by the naked eye, and is the result of the diffaction of light by the periodic patterning of the microwave metamaterial. Credit: Oskar Painter/Caltech

    Newly developed material may be key to scaling up quantum circuits.

    Conventional computers store information in a bit, a fundamental unit of logic that can take a value of 0 or 1. Quantum computers rely on quantum bits, also known as a “qubits,” as their fundamental building blocks. Bits in traditional computers encode a single value, either a 0 or a 1. The state of a qubit, by contrast, can simultaneously have a value of both 0 and 1. This peculiar property, a consequence of the fundamental laws of quantum physics, results in the dramatic complexity in quantum systems.

    Quantum computing is a nascent and rapidly developing field that promises to use this complexity to solve problems that are difficult to tackle with conventional computers. A key challenge for quantum computing, however, is that it requires making large numbers of qubits work together—which is difficult to accomplish while avoiding interactions with the outside environment that would rob the qubits of their quantum properties.

    New research from the lab of Oskar Painter, John G Braun Professor of Applied Physics and Physics in the Division of Engineering and Applied Science, explores the use of superconducting metamaterials to overcome this challenge.

    Metamaterials are specially engineered by combining multiple component materials at a scale smaller than the wavelength of light, giving them the ability to manipulate how particles of light, or photons, behave. Metamaterials can be used to reflect, turn, or focus beams of light in nearly any desired manner. A metamaterial can also create a frequency band where the propagation of photons becomes entirely forbidden, a so-called “photonic bandgap.”

    The Caltech team used a photonic bandgap to trap microwave photons in a superconducting quantum circuit, creating a promising technology for building future quantum computers.

    “In principle, this is a scalable and flexible substrate on which to build complex circuits for interconnecting certain types of qubits,” says Painter, leader of the group that conducted the research, which was published in Nature Communications on September 12. “Not only can one play with the spatial arrangement of the connectivity between qubits, but one can also design the connectivity to occur only at certain desired frequencies.”

    Painter and his team created a quantum circuit consisting of thin films of a superconductor—a material that transmits electric current with little to no loss of energy—traced onto a silicon microchip. These superconducting patterns transport microwaves from one part of the microchip to another. What makes the system operate in a quantum regime, however, is the use of a so-called Josephson junction, which consists of an atomically thin non-conductive layer sandwiched between two superconducting electrodes. The Josephson junction creates a source of microwave photons with two distinct and isolated states, like an atom’s ground and excited electronic states, that are involved in the emission of light, or, in the language of quantum computing, a qubit.

    “Superconducting quantum circuits allow one to perform fundamental quantum electrodynamics experiments using a microwave electrical circuit that looks like it could have been yanked directly from your cell phone,” Painter says. “We believe that augmenting these circuits with superconducting metamaterials may enable future quantum computing technologies and further the study of more complex quantum systems that lie beyond our capability to model using even the most powerful classical computer simulations.”

    The paper is titled “Superconducting metamaterials for waveguide quantum electrodynamics,” The team of authors was led by Mohammad Mirhosseini, a Kavli Nanoscience Institute Postdoctoral Scholar at Caltech. Co-authors include postdoctoral scholars Andrew Keller and Alp Sipahigil of the Institute for Quantum Information and Matter (IQIM); and graduate students Eun Jong Kim, Vinicius Ferreira, and Mahmoud Kalaee. The work was performed as part of a pair of Multidisciplinary University Research Initiatives from the Air Force Office of Scientific Research (“Quantum Photonic Matter” and “Wiring Quantum Networks with Mechanical Transducers”), and in conjunction with IQIM, a National Science Foundation Physics Frontiers Center supported by the Gordon and Betty Moore Foundation.

    See the full article here .


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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 3:06 pm on September 14, 2018 Permalink | Reply
    Tags: , , , Quantum information science on the verge of a technological revolution, Qubits,   

    From UC Santa Cruz: “Quantum information science on the verge of a technological revolution” Revised 

    UC Santa Cruz

    From UC Santa Cruz

    September 13, 2018
    Tim Stephens
    stephens@ucsc.edu

    Theorist Yuan Ping is developing computational methods to guide the design of new materials for quantum computing and other quantum information technologies.

    1
    Materials scientist Yuan Ping (center) with graduate student Tyler Smart (left) and postdoctoral fellow Feng Wu (right) at the UCSC supercomputer center. (Photo by C. Lagattuta)

    See https://sciencesprings.wordpress.com/2018/09/10/from-uc-santa-cruz-nsf-funds-powerful-new-supercomputer-for-uc-santa-cruz-researchers/

    3
    Researchers are racing to develop quantum information technologies, in which information will be stored in quantum bits, or qubits. Qubits can be made from any quantum system that has two states, such as the spin states of electrons. (Image credit: National Science Foundation)

    Quantum computers may one day solve problems that are effectively beyond the capacity of conventional supercomputers. Quantum communications may enable instantaneous, secure transmission of information across vast distances, and quantum sensors may provide previously unheard of sensitivities.

    A global race is on to develop these new quantum information technologies, in which information will be stored in quantum bits, or qubits. In conventional digital technologies, a bit is either 0 or 1, whereas a qubit can represent both states at the same time because of a strange phenomenon of quantum physics called superposition. In theory, this will enable a massive increase in computing speed and capacity for certain types of calculations.

    At UC Santa Cruz, materials scientists are working to develop novel materials that can serve as the foundation for quantum information technology, just as silicon chips paved the way for today’s digital technologies. Several different systems for creating and manipulating qubits have been proposed and implemented, but for now they remain too cumbersome for real-world applications.

    “Our focus as materials scientists is on what material we should use as the fundamental element to carry the information. Other researchers are more concerned with how to wire it up to make a device that can perform calculations, but we’re focused on the material basis of the qubit,” said Yuan Ping, assistant professor of chemistry and biochemistry at UC Santa Cruz.

    2D materials

    In particular, Ping and other UCSC researchers are focusing on defects in extremely thin materials, called two-dimensional (2D) materials. Defects or imperfections in the atomic structure of a material can function as qubits because information can be encoded in the spin states of their electrons. This phenomenon has been well studied in other types of materials, most notably the “nitrogen vacancy” or NV defect in diamond. But according to Ping, 2D materials offer significant advantages.

    “Unlike diamond, 2D materials are relatively cheap and easy to make, they are scalable, and they are easy to integrate into a solid-state device,” she said. “They are also stable at room temperature, which is important because a lot of the qubit systems implemented so far use superconductors that can only operate at very low temperatures.”

    There are a lot of different 2D materials, however, and a lot of ways to put defects into them. The possibilities are almost endless, and it’s not practical to synthesize and test them all experimentally to see which have the best properties for quantum technologies.

    That’s where theorists like Ping come in. She is developing computational methods that can be used to predict the properties of defects in 2D materials reliably and efficiently. In December 2017, her team published a paper in Physical Review Materials establishing the fundamental principles for doing calculations to accurately describe charge defects, electronic states, and spin dynamics in 2D materials. (Her coauthors on the paper include postdoctoral fellow Feng Wu, graduate student Andrew Galatas, and collaborators Dario Rocca at University of Lorraine in France and Ravishankar Sundararaman at Rensselaer Polytechnic Institute.)

    In July, Ping won a $350,000 grant from the National Science Foundation to further develop these computational methods.

    “We’re developing a reliable set of tools to predict the electronic structure, excited-state lifetime, and quantum-state coherence time of defects in 2D materials at a quantum mechanical level,” Ping said. “We do calculations from first principles, meaning we don’t need any input from experiments. Everything is predicted based on quantum mechanics.”

    Quantum weirdness

    The world of quantum mechanics is notoriously counter-intuitive and hard to grasp. Concepts such as superposition and entanglement defy common sense, yet they have been demonstrated conclusively and are fundamental to quantum information technologies. Superposition, when a particle exists in two different states simultaneously, is often compared to a spinning coin, neither heads nor tails until it stops spinning. Entanglement creates a link between the quantum states of two particles or qubits, so it is as if the outcome of one spinning coin determined the outcome of another spinning coin.

    A major challenge in exploiting these phenomena for quantum information technologies is their inherent fragility. Interaction with the environment causes a superposition to fall into one state or the other. Called decoherence, this can be caused by vibrations of the atoms in the material and other subtle effects.

    “You want qubits to be well insulated from the environment to give longer coherence times,” Ping said.

    One 2D material that has shown promise for quantum technologies is ultrathin hexagonal boron nitride. Ping used her computational methods to investigate various defects in this material and identified a promising candidate for scalable quantum applications. This defect (a nitrogen vacancy adjacent to carbon substitution of boron) is predicted to have stable spin states well insulated from the environment and bright optical transitions, making it a good source for single photon emission and a good candidate for qubits.

    “Quantum emitters, which can emit one photon at a time, are important for optically-based quantum information processing, information security, and ultrasensitive sensing,” Ping said.

    She works closely with experimentalists, helping to interpret their results and guide their efforts to create novel materials with desirable properties for quantum technologies. Her group is part of a large collaborative effort, the Quantum Information Science and Engineering Network (QISE-NET), funded by the National Science Foundation. Tyler Smart, a graduate student in Ping’s group, is funded by QISE-NET and is working on a project at Argonne National Laboratory.

    “He will be traveling to Chicago to present his research every few months,” Ping said. “There are about 20 universities as well as national laboratories and industry partners in the network, meeting regularly and sharing ideas, which is important because it’s a fast-moving field.”

    One of the National Science Foundation’s 10 Big Ideas for Future NSF Investments is “The Quantum Leap: Leading the Next Quantum Revolution.”

    The Department of Energy is also investing in this area, as are companies such as Google and Intel, hoping to exploit quantum mechanics to develop next-generation technologies for computing, sensing, and communications.

    “They are all investing in it because it will take a lot of effort to develop this field, and the potential is so great,” Ping said.

    See the full article here .


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    Please help promote STEM in your local schools.

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    UCO Lick Shane Telescope
    UCO Lick Shane Telescope interior
    Shane Telescope at UCO Lick Observatory, UCSC

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    UC Santa Cruz campus
    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

    UCSC is the home base for the Lick Observatory.

    Lick Observatory's Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building
    Lick Observatory’s Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building

    Search for extraterrestrial intelligence expands at Lick Observatory
    New instrument scans the sky for pulses of infrared light
    March 23, 2015
    By Hilary Lebow
    1
    The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch) UCSC Lick Nickel telescope

    Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.

    “Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.

    Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.

    Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.

    Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.

    “The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.

    The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”

    Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.

    “We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”

    Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.

    “This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”

    NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.

    “Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”

    NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.

    The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.

     
  • richardmitnick 12:27 pm on September 6, 2018 Permalink | Reply
    Tags: , , , Quantum gates, , Qubits, , Scientists Have Teleported And Measured a Quantum Gate in Real Time, Teleporting a special quantum operation between two locations,   

    From Yale University via Science Alert: “For The First Time, Scientists Have Teleported And Measured a Quantum Gate in Real Time” 

    Yale University bloc

    From Yale University

    via

    Science Alert

    6 SEP 2018
    MIKE MCRAE

    1
    (agsandrew/istock)

    Welcome to the future.

    Around 20 years ago, two computer scientists proposed a technique for teleporting a special quantum operation between two locations with the goal of making quantum computers more reliable.

    Now a team of researchers from Yale University have successfully turned their idea into reality, demonstrating a practical approach to making this incredibly delicate form of technology scalable.

    These physicists have developed a practical method for teleporting a quantum operation – or gate – across a distance and measuring its effect. While this feat has been done before, it’s never been done in real time. This paves the way for developing a process that can make quantum computing modular, and therefore more reliable.

    Unlike regular computers, which perform their calculations with states of reality called bits (on or off, 1 or 0), quantum computers operate with qubits – a strange state of reality we can’t wrap our heads around, but which taps into some incredibly useful mathematics.

    In classical computers, bits interact with operations called logic gates. Like the world’s smallest gladiatorial arena, two bits enter, one bit leaves. Gates come in different forms, selecting a winner depending on their particular rule.

    These bits, channelled through gates, form the basis of just about any calculation you can think of, as far as classical computers are concerned.

    But qubits offer an alternative unit to base algorithms on. More than just a 1 or a 0, they also provide a special blend of the two states. It’s like a coin held in a hand before you see whether it’s heads or tails.

    In conjunction with a quantum version of a logic gate, qubits can do what classical bits can’t. There’s just one problem – that indeterminate state of 1 and 0 turns into a definite 1 or 0 when it becomes part of a measured system.

    Worse still, it doesn’t take much to collapse the qubit’s maybe into a definitely, which means a quantum computer can become an expensive paperweight if those delicate components aren’t adequately hidden from their noisy environment.

    Right now, quantum computer engineers are super excited by devices that can wrangle just over 70 qubits – which is impressive, but quantum computers will really only earn their keep as they stock up on hundreds, if not thousands of qubits all hovering on the brink of reality at the same time.

    To make this kind of scaling a reality, scientists need additional tricks. One option would be to make the technology as modular as possible, networking smaller quantum systems into a bigger one in order to offset errors.

    But for that to work, quantum gates – those special operations that deal with the heavy lifting of qubits – also need to be shared.

    Teleporting information, such as a quantum gate, sounds pretty sci-fi. But we’re obviously not talking about Star Trek transport systems here.

    In reality it simply refers to the fact that objects can have their history entangled so that when one is measured, the other immediately collapses into a related state, no matter how far away it is.

    This has technically been demonstrated experimentally already [Physical Review Letters], but, until now, the process hasn’t been reliably performed and measured in real time, which is crucial if it’s to become part of a practical computer.

    “Our work is the first time that this protocol has been demonstrated where the classical communication occurs in real-time, allowing us to implement a ‘deterministic’ operation that performs the desired operation every time,” says lead author Kevin Chou.

    The researchers used qubits in sapphire chips inside a cutting-edge setup to teleport a type of quantum operation called a controlled-NOT gate. Importantly, by applying error-correctable coding, the process was 79 percent reliable.

    “It is a milestone toward quantum information processing using error-correctable qubits,” says principal investigator Robert Schoelkopf.

    It’s a baby step on the road to making quantum modules, but this proof-of-concept shows modules could still be the way to go in growing quantum computers to the scale we need.

    This research was published in Nature.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Yale University Campus

    Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

     
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