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Category: computing – Page 573

Fault-tolerant logic gates will consume a large proportion of the resources of a two-dimensional quantum computing architecture. Here we show how to perform a fault-tolerant non-Clifford gate with the surface code; a quantum error-correcting code now under intensive development. This alleviates the need for distillation or higher-dimensional components to complete a universal gate set. The operation uses both local transversal gates and code deformations over a time that scales with the size of the qubit array. An important component of the gate is a just-in-time decoder. These decoding algorithms allow us to draw upon the advantages of three-dimensional models using only a two-dimensional array of live qubits. Our gate is completed using parity checks of weight no greater than four. We therefore expect it to be amenable with near-future technology. As the gate circumvents the need for magic-state distillation, it may reduce the resource overhead of surface-code quantum computation considerably.

A scalable quantum computer is expected to solve difficult problems that are intractable with classical technology. Scaling such a machine to a useful size will necessarily require fault-tolerant components that protect quantum information as the data is processed (1–4). If we are to see the realization of a quantum computer, its design must respect the constraints of the quantum architecture that can be prepared in the laboratory. In many cases, for instance, superconducting qubits (5–7), this restricts us to two-dimensional architectures.

Leading candidate models for fault-tolerant quantum computation are based on the surface code (3, 8) due to its high threshold (9) and multitude of ways of performing Clifford gates (10). Universal quantum computation is possible if this gate set is supplemented by a non-Clifford gate. Among the most feasible approaches to realize a non-Clifford gate is by the use of magic-state distillation (11). However, this is somewhat prohibitive as a large fraction of the resources of a quantum computer will be expended by these protocols (12, 13).

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Microsoft today announced that Azure Quantum, its partner-centric quantum computing platform for developers who want to get started with quantum computing, is now in limited preview. First announced at Microsoft Ignite 2019, Azure Quantum brings together the hardware from IonQ, Honeywell, QCI and Microsoft, services from the likes of 1QBit, and the classical computing capabilities of the Azure cloud. With this move to being in limited preview, Microsoft is now opening the service up to a small number of select partners and customers.

At its current stage, quantum computing isn’t exactly a mission-critical capability for any business, but given how fast things are moving and how powerful the technology will be once it’s matured a bit over the next few years, many experts argue that now is the time to get started — especially because of how different quantum computing is from classical computing and how it will take developers a while to develop.

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Error suppression opens pathway to universal quantum computing.

A scientist at the University of Sydney has achieved what one quantum industry insider has described as “something that many researchers thought was impossible.”

Dr. Benjamin Brown from the School of Physics has developed a type of error-correcting code for quantum computers that will free up more hardware to do useful calculations. It also provides an approach that will allow companies like Google and IBM to design better quantum microchips.

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Physicists at the National Institute of Standards and Technology have boosted their control of the fundamental properties of molecules at the quantum level by linking or “entangling” an electrically charged atom and an electrically charged molecule, showcasing a way to build hybrid quantum information systems that could manipulate, store and transmit different forms of data.

Described in a Nature paper posted online May 20, the new NIST method could help build large-scale quantum computers and networks by connecting quantum bits (qubits) based on otherwise incompatible hardware designs and operating frequencies. Mixed-platform quantum systems could offer versatility like that of conventional computer systems, which, for example, can exchange data among an electronic processor, an optical disc, and a magnetic hard drive.

The NIST experiments successfully entangled the properties of an electron in the atomic ion with the rotational states of the molecule so that measurements of one particle would control the properties of the other. The research builds on the same group’s 2017 demonstration of quantum control of a molecule, which extended techniques long used to manipulate atoms to the more complicated and potentially more fruitful arena offered by molecules, composed of multiple atoms bonded together.

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To many developers, quantum computing may still feel like a futuristic technology shrouded in mystery and surrounded by hype. It’s some mystic dance of 1s and 0s that will enable some calculations in mere hours that today would take the lifetime of the universe to compute. It’s somehow related to a cat that may or may not be dead in a box.

The question we hear most often from developers is how do you make sense of what’s real and get started?

Over the last year, we’ve been working with you, the pioneering community of quantum developers, to understand what all developers will need on the path to scalable quantum computing. You’ve told us that you want to learn more about where quantum could impact your business today, to have easier ways to start writing quantum code, and to run applications against a range of quantum and classical hardware.

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Scientists are using light waves to accelerate supercurrents and access the unique properties of the quantum world, including forbidden light emissions that one day could be applied to high-speed, quantum computers, communications and other technologies.

The scientists have seen unexpected things in supercurrents—electricity that moves through materials without resistance, usually at super cold temperatures—that break symmetry and are supposed to be forbidden by the conventional laws of physics, said Jigang Wang, a professor of physics and astronomy at Iowa State University, a senior scientist at the U.S. Department of Energy’s Ames Laboratory and the leader of the project.

Wang’s lab has pioneered use of light pulses at terahertz frequencies- trillions of pulses per second—to accelerate electron pairs, known as Cooper pairs, within supercurrents. In this case, the researchers tracked light emitted by the accelerated electrons pairs. What they found were “second harmonic ,” or light at twice the frequency of the incoming light used to accelerate electrons.

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It sounds like a riddle: What do you get if you take two small diamonds, put a small magnetic crystal between them and squeeze them together very slowly?

The answer is a magnetic liquid, which seems counterintuitive. Liquids become solids under pressure, but not generally the other way around. But this unusual pivotal discovery, unveiled by a team of researchers working at the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility at DOE’s Argonne National Laboratory, may provide scientists with new insight into and quantum computing.

Though scientists and engineers have been making use of superconducting materials for decades, the exact process by which conduct electricity without resistance remains a quantum mechanical mystery. The telltale signs of a superconductor are a loss of resistance and a loss of magnetism. High-temperature superconductors can operate at temperatures above those of (−320 degrees Fahrenheit), making them attractive for lossless transmission lines in power grids and other applications in the energy sector.

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Computer systems that can automatically generate image captions have been around for several years. While many of these techniques perform considerably well, the captions they produce are typically generic and somewhat uninteresting, containing simple descriptions such as “a dog is barking” or “a man is sitting on a bench.”

Alasdair Tran, Alexander Mathews and Lexing Xie at the Australian National University have been trying to develop new systems that can generate more sophisticated and descriptive image captions. In a paper recently pre-published on arXiv, they introduced an automatic captioning system for news images that takes the general context behind an image into account while generating new captions. The goal of their study was to enable the creation of captions that are more detailed and more closely resemble those written by humans.

“We want to go beyond merely describing the obvious and boring visual details of an image,” Xie told TechXplore. “Our lab has already done work that makes image captions sentimental and romantic, and this work is a continuation on a different dimension. In this new direction, we wanted to focus on the context.”

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