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  • richardmitnick 9:38 am on July 3, 2020 Permalink | Reply
    Tags: At RIKEN a superconducting circuit with an element called a Josephson junction is used to create a useful quantum-mechanical effect., At RIKEN we have built a four-by-four array of qubits using our own wiring scheme., Last year Google produced a 53-qubit quantum computer that could perform a specific calculation significantly faster than the world’s fastest supercomputer., Quantum computers, , The Google system boasts tens of qubits—the quantum counterparts to bits.   

    From RIKEN: “Wiring a new path to scalable quantum computing” 

    RIKEN bloc

    From RIKEN

    Clever wiring architecture will soon produce bigger and better quantum circuits, says Yasunobu Nakamura.

    Jul. 3, 2020
    Yasunobu Nakamura, Team Leader, Superconducting Quantum Electronics Research Team

    Last year, Google produced a 53-qubit quantum computer that could perform a specific calculation significantly faster than the world’s fastest supercomputer. Like most of today’s largest quantum computers, this system boasts tens of qubits—the quantum counterparts to bits, which encode information in conventional computers.

    To make larger and more useful systems, most of today’s prototypes will have to overcome the challenges of stability and scalability. The latter will require increasing the density of signaling and wiring, which is hard to do without degrading the system’s stability. I believe a new circuit-wiring scheme developed over the last three years by RIKEN’s Superconducting Quantum Electronics Research Team, in collaboration with other institutes, opens the door to scaling up to 100 or more qubits within the next decade. Here, I discuss how.

    1
    This schematic image of integrated superconducting qubits and their packaging,shows the qubits as green dots with rings, which are laid out on top of a silicon chip (in red). A number of holes through the chip electrically connect the top and bottom surfaces. The blue wires on top are circuit elements for the readout of the qubits. Coaxial wiring (with gold-plated springloaded pins) is connected to the backside of the chip, and these control and read the qubits. © Yutaka Tabuchi

    Challenge one: Scalability

    Image of quantum circuit [above]. This schematic image of integrated superconducting qubits and their packaging,shows the qubits as green dots with rings, which are laid out on top of a silicon chip (in red). A number of holes through the chip electrically connect the top and bottom surfaces. The blue wires on top are circuit elements for the readout of the qubits. Coaxial wiring (with gold-plated springloaded pins) is connected to the backside of the chip, and these control and read the qubits. © Yutaka Tabuchi

    Quantum computers process information using delicate and complex interactions based on the principles of quantum mechanics. To explain this further we must understand qubits. A quantum computer is built from individual qubits, which are analogous to the binary bits used in conventional computers. But instead of the zero or one binary states of a bit, a qubit needs to maintain a very fragile quantum state. Rather than just being zero or one, qubits can also be in a state called a superposition—where they are sort of in a state of both zero and one at the same time. This allows quantum computers based on qubits to process data in parallel for each possible logical state, zero or one, and they can thus perform more efficient, and thus faster, calculations than conventional computers based on bits for particular types of problems.

    However, it is much harder to create a qubit than a conventional bit, and full control over the quantum-mechanical behavior of a circuit is needed. Scientists have come up with a few ways to do this with some reliability. At RIKEN, a superconducting circuit with an element called a Josephson junction is used to create a useful quantum-mechanical effect. In this way, qubits can now be produced reliably and repeatedly with nanofabrication techniques commonly used in the semiconductor industry.

    The challenge of scalability arises from the fact that each qubit then needs wiring and connections that produce controls and readouts with minimal crosstalk. As we moved past tiny two-by-two or four-by-four arrays of qubits, we have realized just how densely the associated wiring can be packed, and we’ve had to create better systems and fabrication methods to avoid getting our wires crossed, literally.

    At RIKEN, we have built a four-by-four array of qubits using our own wiring scheme, where the connections to each qubit are made vertically from the backside of a chip, rather than a separate ‘flip chip’ interface used by other groups that brings the wiring pads to the edges of a quantum chip. This involves some sophisticated fabrication with a dense array of superconducting vias (electrical connections) through a silicon chip, but it should allow us to scale up to much larger devices. Our team is working toward a 64-qubit device, which we hope to have within the next three years. This will be followed by a 100-qubit device in another five years as part of a nationally funded research program. This platform should ultimately allow up to a 1,000 qubits to be integrated on a single chip.

    Challenge two: Stability

    The other major challenge for quantum computers is how to deal with the intrinsic vulnerability of the qubits to fluctuations or noise from outside forces such as temperature. For a qubit to function, it needs to be maintained in a state of quantum superposition, or ‘quantum coherence’. In the early days of superconducting qubits, we could make this state last for just nanoseconds. Now, by cooling quantum computers to cryogenic temperatures and creating several other environmental controls, we can maintain coherence for up to 100 microseconds. A few hundred microseconds would allow us to perform a few thousand information processing operations, on average, before coherence is lost.

    In theory, one way we could deal with instability is to use quantum error correction, where we exploit several physical qubits to encode a single ‘logical qubit’, and apply an error correction protocol that can diagnose and fix errors to protect the logical qubit. But realizing this is still far off for many reasons, not the least of which is the problem of scalability.

    Quantum circuits

    Since the 1990s, before quantum computing became a big thing. When I began, I was interested in whether my team could create and measure quantum superposition states within electric circuits. At the time, it wasn’t at all obvious if electric circuits as a whole could behave quantum mechanically. To realize a stable qubit in a circuit and create switch-on and -off states in the circuit, the circuit also needed to be capable of supporting a superposition state.

    We eventually came up with the idea of using a superconducting circuit. The superconducting state is free of all electrical resistance and losses, and so it is streamlined to respond to small quantum-mechanical effects. To test this circuit, we used a microscale superconducting island made of aluminum, which was connected to a larger superconducting ground electrode via a Josephson junction—a junction separated by a nanometer-thick insulating barrier—and we trapped superconducting electron pairs that tunneled across the junction. Because of the smallness of the aluminum island, it could accommodate at most one excess pair due to an effect known as Coulomb blockade between negatively charged pairs. The states of zero or one excess pairs in the island can be used as the state of a qubit. The quantum-mechanical tunneling maintains the qubit’s coherence and allows us to create a superposition of the states, which is fully controlled with microwave pulses.

    Hybrid systems

    Because of their very delicate nature, quantum computers are unlikely to be in homes in the near future. However, recognizing the huge benefits of research-oriented quantum computers, industrial giants such as Google and IBM, as well as many start-up companies and academic institutes around the world, are increasingly investing in research.

    A commercial quantum-computing platform with full error correction is probably still more than a decade away, but state-of-the-art technical developments are already bringing about the possibility of new science and applications. Smaller scale quantum circuits already perform useful tasks in the lab.

    For example, we use our superconducting quantum-circuit platform in combination with other quantum-mechanical systems. This hybrid quantum system allows us to measure a single quantum reaction within collective excitations—be it precessions of electron spins in a magnet, crystal lattice vibrations in a substrate, or electromagnetic fields in a circuit—with unprecedented sensitivity. These measurements should advance our understanding of quantum physics, and with it quantum computing. Our system is also sensitive enough to measure a single photon at microwave frequencies, whose energy is about five orders of magnitude lower than that of a visible-light photon, without absorbing or destroying it. The hope is that this will serve as a building block for quantum networks connecting distant qubit modules, among other things.

    Quantum internet

    Interfacing a superconducting quantum computer to an optical quantum communication network is another future challenge for our hybrid system. This would be developed in anticipation of a future that includes a quantum internet connected by optical wiring reminiscent of today’s internet. However, even a single photon of infrared light at a telecommunication wavelength cannot directly hit a superconducting qubit without disturbing the quantum information, so careful design is a must. We are currently investigating hybrid quantum systems that transduce quantum signals from a superconducting qubit to an infrared photon, and vice versa, via other quantum systems, such as one that involves a tiny acoustic oscillator.

    Although many complex issues need to be overcome, scientists can see a future enhanced by quantum computers on the horizon. In fact, quantum science is already in our hands every day. Transistors and laser diodes would have never been invented without a proper understanding of the properties of electrons in semiconductors, which is totally based on understanding quantum mechanics. So through smart phones and the internet, we are already totally reliant on quantum mechanics, and we will only become more so in the future.

    References

    1.Nakamura, Y., Pashkin, Y. A. & Tsai, J. S. Coherent control of macroscopic quantum states in a single-Cooper-pair box Nature 398, 786–788 (1999) doi: 10.1038/19718The webpage will open in a new tab.
    2. Clerk, A. A., Lehnert, K. W, Berte, P., Petta, J. R & Nakamura, Y. Hybrid quantum systems with circuit quantum electrodynamics Nature Physics 16, 257-267 (2020). doi: 10.1038/s41567-020-0797-9The webpage will open in a new tab.
    3. Lachance-Quirion, D., Wolski, S. P., Tabuchi, Y., Kono, S., Usami, K. & Njavascript:void(0)akamura Y. Entanglement-based single-shot detection of a single magnon with a superconducting qubit Science 367, 425-428 (2020). doi: 10.1126/science.aaz9236The webpage will open in a new tab.
    4.Noguchi, A., Yamazaki, R., Tabuchi, Y. & Nakamura, Y. Qubit-assisted transduction for a detection of surface acoustic waves near the quantum limit Phys. Rev. Lett 119, 180505 (2017). doi: 10.1103/PhysRevLett.119.180505The webpage will open in a new tab.
    5. Kono, S., Koshino, K., Tabuchi, Y., Noguchi, A. & Nakamura, Y. Quantum non-demolition detection of an itinerant microwave photon Nature Physics 14, 546-549 (2018). doi: 10.1038/s41567-018-0066-3

    See the full article here .


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    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 12:39 pm on May 18, 2020 Permalink | Reply
    Tags: "UCLA physicists develop world’s best quantum bits", , Quantum computers,   

    From UCLA: “UCLA physicists develop world’s best quantum bits” 

    UCLA bloc

    From UCLA

    1
    Assistant Professor Wesley Campbell, UCLA Physics & Astronomy (Photo Credit: UCLA)

    A team of researchers at UCLA has set a new record for preparing and measuring the quantum bits, or qubits, inside of a quantum computer without error. The techniques they have developed make it easier to build quantum computers that outperform classical computers for important tasks, including the design of new materials and pharmaceuticals. The research is published in the peer-reviewed, online open-access journal, npj Quantum Information, published by Nature and including the exceptional research on quantum information and quantum computing.

    Currently, the most powerful quantum computers are “noisy intermediate-scale quantum” (NISQ) devices and are very sensitive to errors. Error in preparation and measurement of qubits is particularly onerous: for 100 qubits, a 1% measurement error means a NISQ device will produce an incorrect answer about 63% of the time, said senior author Eric Hudson, a UCLA professor of physics and astronomy.

    To address this major challenge, Hudson and UCLA colleagues recently developed a new qubit hosted in a laser-cooled, radioactive barium ion. This “goldilocks ion” has nearly ideal properties for realizing ultra-low error rate quantum devices, allowing the UCLA group to achieve a preparation and measurement error rate of about 0.03%, lower than any other quantum technology to date, said co-senior author Wesley Campbell, also a UCLA professor of physics and astronomy.

    The development of this exciting new qubit at UCLA should impact almost every area of quantum information science, Hudson said. This radioactive ion has been identified as a promising system in quantum networking, sensing, timing, simulation and computation, and the researchers’ paper paves the way for large-scale NISQ devices.

    Co-authors are lead author Justin Christensen, a postdoctoral scholar in Hudson’s laboratory, and David Hucul, a former postdoctoral scholar in Hudson and Campbell’s laboratories, who is now a physicist at the U.S. Air Force Research Laboratory.

    The research is funded by the U.S. Army Research Office.

    Campbell and Hudson are primary investigators of a major $2.7 million U.S. Department of Energy Quantum Information Science Research project to lay the foundation for the next generation of computing and information processing, as well as many other innovative technologies.

    See the full article here .

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    For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

     
  • richardmitnick 12:51 pm on December 18, 2019 Permalink | Reply
    Tags: "Remote Quantum Systems Produce Interfering Photons", , , , , , , Quantum computers, ,   

    From Joint Quantum Institute: “Remote Quantum Systems Produce Interfering Photons” 

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    From Joint Quantum Institute

    December 17, 2019

    Research Contact
    Steve Rolston
    rolston@umd.edu

    Story by Jillian Kunze

    1
    A schematic showing the paths taken by photons from two different sources in neighboring buildings. (Credit: S. Kelley/NIST)

    Scientists at the Joint Quantum Institute (JQI) have observed, for the first time, interference between particles of light created using a trapped ion and a collection of neutral atoms. Their results could be an essential step toward the realization of a distributed network of quantum computers capable of processing information in novel ways.

    In the new experiment, atoms in neighboring buildings produced photons—the quantum particles of light—in two distinct ways. Several hundred feet of optical cables then brought the photons together, and the research team, which included scientists from JQI as well as the Army Research Lab, measured a telltale interference pattern. It was the first time that photons from these two particular quantum systems were manipulated into having the same wavelength, energy and polarization—a feat that made the particles indistinguishable. The result, which may prove vital for communicating over quantum networks of the future, was published recently in the journal Physical Review Letters.

    “If we want to build a quantum internet, we need to be able to connect nodes of different types and functions,” says JQI Fellow Steve Rolston, a co-author of the paper and a professor of physics at the University of Maryland. “Quantum interference between photons generated by the different systems is necessary to eventually entangle the nodes, making the network truly quantum.”

    The first source of photons was a single trapped ion—an atom that is missing an electron—held in place by electric fields. Collections of these ions, trapped in a chain, are leading candidates for the construction of quantum computers due to their long lifetimes and ease of control. The second source of photons was a collection of very cold atoms, still in possession of all their electrons. These uncharged, or neutral, atomic ensembles are excellent interfaces between light and matter, as they easily convert photons into atomic excitations and vice versa. The photons produced by each of these two systems are typically different, limiting their ability to work together.

    In one building, researchers used a laser to excite a trapped barium ion to a higher energy. When it transitioned back to a lower energy, it emitted a photon at a known wavelength but in a random direction. When scientists captured a photon, they stretched its wavelength to match photons from the other source.

    In an adjacent building, a cloud of tens of thousands of neutral rubidium atoms generated the photons. Lasers were again used to pump up the energy of these atoms, and that procedure imprinted a single excitation across the whole cloud through a phenomenon called the Rydberg blockade. When the excitation shed its energy as photons, they traveled in a well-defined direction, making it easy for researchers to collect them.

    The team used an interferometer to measure the degree to which two photons were identical. A single photon entering the interferometer is equally likely to take either of two possible exits. And two distinguishable photons entering the interferometer at the same time don’t notice each other, acting like two independent single photons.

    But when researchers brought together the photons from their two sources, they almost always took the same exit—a result of quantum interference and an indication that they were nearly identical. This was precisely what the research team had hoped for: the first demonstration of interference between photons from these two very different quantum systems.

    In this experiment, photons traveled from the first building to the second via hundreds of feet of optical fiber. Due to this distance, sending photons from both systems to meet at the interferometer simultaneously was a feat of precise timing. Detectors were placed at the exits of the interferometer to detect where the photons came out, but the team often had to wait—gathering all the data took 24 hours over a period of 3 days.

    Further experimental upgrades could be used to generate a special quantum connection called entanglement between the ion and the neutral atoms. In entanglement, two quantum objects become so closely linked that the results from measuring one are correlated with the results from measuring the other, even if the objects are separated by a huge distance. Entanglement is necessary for the speedy algorithms that scientists hope to run on quantum computers in the future.

    Generating entanglement between different quantum systems usually requires identical photons, which the researchers were able to create. Unfortunately, trapped ions emit photons in a random direction, making the probability of catching them low. This meant that only about eight photons from the trapped ion made it to the interferometer each second. If the researchers attempted to perform more intricate experiments with that rate, the data could take months to collect. However, future work may increase how frequently the ion emits photons and allow for a useful rate of entanglement production.

    “This is a stepping-stone on the way to being able to entangle these two systems,” says Alexander Craddock, a graduate student at JQI and the lead author of this study. “And that would be fantastic, because you can then take advantage of all the different weird and wonderful properties of both of them.”

    In addition to Rolston and Craddock, co-authors of the paper include JQI graduate students John Hannegan, Dalia Ornelas-Huerta, and Andrew Hachtel, JQI postdoctoral researcher James Siverns, Army Research Laboratory scientists and JQI Affiliates Elizabeth Goldschmidt (now an Assistant Professor of Physics at the University of Illinois) and Qudsia Quraishi, and JQI Fellow Trey Porto.

    See the full article here .


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    JQI supported by Gordon and Betty Moore Foundation

    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 3:22 pm on March 13, 2019 Permalink | Reply
    Tags: "Quantum computing should supercharge this machine-learning technique", , Certain machine-learning tasks could be revolutionized by more powerful quantum computers., , , Quantum computers   

    From M.I.T Technology Review: “Quantum computing should supercharge this machine-learning technique” 

    MIT Technology Review
    From M.I.T Technology Review

    March 13, 2019
    Will Knight

    1
    The machine-learning experiment was performed using this IBM Q quantum computer.

    Certain machine-learning tasks could be revolutionized by more powerful quantum computers.

    Quantum computing and artificial intelligence are both hyped ridiculously. But it seems a combination of the two may indeed combine to open up new possibilities.

    In a research paper published today in the journal Nature, researchers from IBM and MIT show how an IBM quantum computer can accelerate a specific type of machine-learning task called feature matching. The team says that future quantum computers should allow machine learning to hit new levels of complexity.

    As first imagined decades ago, quantum computers were seen as a different way to compute information. In principle, by exploiting the strange, probabilistic nature of physics at the quantum, or atomic, scale, these machines should be able to perform certain kinds of calculations at speeds far beyond those possible with any conventional computer (see “What is a quantum computer?”). There is a huge amount of excitement about their potential at the moment, as they are finally on the cusp of reaching a point where they will be practical.

    At the same time, because we don’t yet have large quantum computers, it isn’t entirely clear how they will outperform ordinary supercomputers—or, in other words, what they will actually do (see “Quantum computers are finally here. What will we do with them?”).

    Feature matching is a technique that converts data into a mathematical representation that lends itself to machine-learning analysis. The resulting machine learning depends on the efficiency and quality of this process. Using a quantum computer, it should be possible to perform this on a scale that was hitherto impossible.

    The MIT-IBM researchers performed their simple calculation using a two-qubit quantum computer. Because the machine is so small, it doesn’t prove that bigger quantum computers will have a fundamental advantage over conventional ones, but it suggests that would be the case, The largest quantum computers available today have around 50 qubits, although not all of them can be used for computation because of the need to correct for errors that creep in as a result of the fragile nature of these quantum bits.

    “We are still far off from achieving quantum advantage for machine learning,” the IBM researchers, led by Jay Gambetta, write in a blog post. “Yet the feature-mapping methods we’re advancing could soon be able to classify far more complex data sets than anything a classical computer could handle. What we’ve shown is a promising path forward.”

    “We’re at stage where we don’t have applications next month or next year, but we are in a very good position to explore the possibilities,” says Xiaodi Wu, an assistant professor at the University of Maryland’s Joint Center for Quantum Information and Computer Science. Wu says he expects practical applications to be discovered within a year or two.

    Quantum computing and AI are hot right now. Just a few weeks ago, Xanadu, a quantum computing startup based in Toronto, came up with an almost identical approach to that of the MIT-IBM researchers, which the company posted online. Maria Schuld, a machine-learning researcher at Xanadu, says the recent work may be the start of a flurry of research papers that combine the buzzwords “quantum” and “AI.”

    “There is a huge potential,” she says.

    See the full article here .


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  • richardmitnick 11:27 am on September 27, 2018 Permalink | Reply
    Tags: , Atom-based quantum computer, , , Quantum computers, , , 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 11:39 am on August 10, 2018 Permalink | Reply
    Tags: Centre of Excellence for Quantum Computation and Communication Technology, Professor Michelle Simmons, Quantum computers, ,   

    From University of New South Wales: Women in STEM- “School students get exclusive insights into the world of quantum” Professor Michelle Simmons 

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    From University of New South Wales

    10 Aug 2018
    Isabelle Dubach

    Hundreds of school students got a rare peek into what life as a scientist could be like, as Professor Michelle Simmons opened the doors of the Centre of Excellence for Quantum Computation and Communication Technology ahead of National Science Week.

    1
    Professor Simmons, Eddie Woo and the Simmons class.

    When Scientia Professor Michelle Simmons became Australian of the Year 2018, her acceptance speech touched on themes that resonated with many school students and teachers: her encouragement of all young people to pursue what they love, to set their sights high, to tackle the hardest challenges in life and to be the creators – not just the users – of technology.

    Following the ceremony – and numerous subsequent speech invites from schools across Australia – Professor Simmons and her team decided to open the doors of the Centre for Quantum Computation and Communication Technology for one full day, to offer students the opportunity to see the team’s groundbreaking research in action – a first in the centre’s history.

    Professor Simmons said the goal was to open the students’ minds to the possibilities a career in STEM offers.

    “When I was younger, I got to see a fabrication plant in the US, and observed how they make semi-conductor chips. It completely opened my mind to the world of possibility that was out there. I remember thinking that all children should see this.

    “So here we are in Australia, we’ve got this great facility of building chips in-house, so I’m hoping we opened the students’ eyes to what’s out there, to all the kind of jobs they can have, and just get them excited by science.”

    A rare view into quantum labs

    The day was jam-packed, with primary school students visiting the centre in the morning, and secondary students following in the afternoon. After an official welcome and a mini-lecture by Michelle Simmons, the first school group was led through the quantum laboratories to witness the technology being used to build a quantum computer in silicon.

    The students were led through a range of different labs – each one dedicated to building and testing different components of the silicon quantum computer chip. This includes the Scanning Tunnelling Microscope “Atom” lab where the atoms are placed precisely onto a silicon chip, the Clean Rooms where miniature wires are added to the silicon chips, and the “Cryo” Fridge Lab, which tests the electrical response of the atom qubits in fridges at temperatures close to -273 degree C.

    2
    3
    4
    Students in the CQC2T labs.

    Enlightening workshops and experiments

    Students also embarked on a series of interactive workshops and presentations. Hands-on experiments included a ‘silicon full clean’ station, where students got an insight into the day-to-day of the centre’s researchers by helping clean silicon samples. In another experiment, research staff cooled down several everyday objects – like fruit and marshmallow – with liquid nitrogen, to show students how materials react to different temperatures. Students were fascinated to observe how the fruit, for example, becomes very brittle when exposed to nitrogen.

    5
    Students participating in experiments.

    6
    Students at the ‘silicon full clean’ station.

    Special guest and star maths teacher Eddie Woo showed the students a mind-blowing card trick to illustrate fundamental principles of maths.

    “By showing the kids some practical mathematics with something as simple as a deck of cards, I’m hoping to have demonstrated to them that there are patterns all around them in the universe – some of them seem invisible but once you have an eye to perceive them, the possibilities are endless,” Eddie said.

    “What I hope the children take away from today is that mathematics is found everywhere and it’s for everyone. I think people walk through their life not realising that they swim in this ocean of numbers and shapes that are there to be understood and appreciated.

    “We also fall for the misconception that there’s a certain kind of person who’s a maths person and the rest of us are just normal and can’t comprehend all this. I don’t believe that, I think maths is for everyone, and it’s something we can all embrace.

    “In fact, mathematics is the gateway that allows us to solve these really profound and world-changing problems, like trying to construct a quantum computer!”

    7
    Eddie Woo explaining a card trick.

    Special guests from Victoria

    Among the 200 students visiting the centre was a group of special guests: the Simmons Class, a year 2 class from St Mary of the Cross Primary School in Point Cook, Victoria. Every year, the school names their classes after inspiring themes and individuals – and this year, under the theme of Australian scientists, this class named themselves “Simmons”.

    Earlier this year, Michelle went to see the “Simmons” class in Point Cook, and invited them to visit the centre on Open Day. Many of the children had never been on a plane before.

    The school’s principal, Leon Colla, said that seeing the centre’s research in action was a great experience for the children.

    “I hope that the children will take out of today that science is incredibly important for our future as a country and for them as leaders of the future – and that science is a great pathway to take in education.”

    8
    Simmons class students in the CQC2T labs.

    The school’s teacher, Jennifer Ryan, who had kickstarted the visit by simply emailing Professor Simmons, said interacting with Michelle and the research had created a renewed passion in her students to try new things, be problem solvers, and open up to risk-taking.

    “They’ve learned a lot about quantum physics as a grade 2, and their interest in science has just escalated. Just coming here today I can see how much they’ve picked up on Michelle’s work because they can relate to what they’re seeing.

    “I hope they take out of today that they should dream big. I catch myself looking around, thinking what an incredible opportunity we’ve received – so I hope my students always think that anything’s possible with hard work and putting your mind to it.”

    The positive sentiment was echoed by one student’s dad, James Wetherill, who said his daughter Megan was – to use one of her own words – ‘nerve-cited’ to visit the centre.

    “She was really nervous, and, exceptionally excited as well. She went and bought herself a science kit over the weekend and sat there with her goggles on and said she was practising for coming up today, so she’s loved it, she’s been fully involved, and hopefully it helps guide her moving forward.”

    Another student’s mum, Shella Martin, said the journey her family had been on with Michelle Simmons had been phenomenal.

    “This is basically a dream come true for us. Charlton has always said he was going to be a scientist and mathematician, but he hadn’t seen that come true in any other moment until now.

    “To be able to incorporate this into his education, to show him the potential of the things he can do when he’s older, is just amazing, so we’re just so happy to be able to have this opportunity.”

    9
    Simmons class students.

    Professor Michelle Simmons is delivering the Einstein Lecture as part of Science Week on Tuesday 14 August, 6-7.15pm, at UNSW Sydney. The event is sold out, but you can put your name on a waiting list.

    See the full article here .


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    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 10:41 am on February 19, 2018 Permalink | Reply
    Tags: , , , , Quantum computers,   

    From phys.org: “Unconventional superconductor may be used to create quantum computers of the future” 

    physdotorg
    phys.org

    February 19, 2018

    1
    After an intensive period of analyses the research team led by Professor Floriana Lombardi, Chalmers University of Technology, was able to establish that they had probably succeeded in creating a topological superconductor. Credit: Johan Bodell/Chalmers University of Technology

    With their insensitivity to decoherence, Majorana particles could become stable building blocks of quantum computers. The problem is that they only occur under very special circumstances. Now, researchers at Chalmers University of Technology have succeeded in manufacturing a component that is able to host the sought-after particles.

    Researchers throughout the world are struggling to build quantum computers. One of the great challenges is to overcome the sensitivity of quantum systems to decoherence, the collapse of superpositions. One track within quantum computer research is therefore to make use of Majorana particles, which are also called Majorana fermions. Microsoft, among other organizations, is exploring this type of quantum computer.

    Majorana fermions are highly original particles, quite unlike those that make up the materials around us. In highly simplified terms, they can be seen as half-electron. In a quantum computer, the idea is to encode information in a pair of Majorana fermions separated in the material, which should, in principle, make the calculations immune to decoherence.

    So where do you find Majorana fermions? In solid state materials, they only appear to occur in what are known as topological superconductors. But a research team at Chalmers University of Technology is now among the first in the world to report that they have actually manufactured a topological superconductor.

    “Our experimental results are consistent with topological superconductivity,” says Floriana Lombardi, professor at the Quantum Device Physics Laboratory at Chalmers.

    To create their unconventional superconductor, they started with what is called a topological insulator made of bismuth telluride, Be2Te3. A topological insulator conducts current in a very special way on the surface. The researchers placed a layer of aluminum, a conventional superconductor, on top, which conducts current entirely without resistance at low temperatures.

    “The superconducting pair of electrons then leak into the topological insulator, which also becomes superconducting,” explains Thilo Bauch, associate professor in quantum device physics.

    However, the initial measurements all indicated that they only had standard superconductivity induced in the Bi2Te3 topological insulator. But when they cooled the component down again later, to routinely repeat some measurements, the situation suddenly changed—the characteristics of the superconducting pairs of electrons varied in different directions.

    “And that isn’t compatible at all with conventional superconductivity. Unexpected and exciting things occurred,” says Lombardi.

    “For practical applications, the material is mainly of interest to those attempting to build a topological quantum computer. We want to explore the new physics hidden in topological superconductors—this is a new chapter in physics,” Lombardi says.

    The results were recently published in Nature Communications in a study titled “Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator.”

    See the full article here .

    Please help promote STEM in your local schools.

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
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