Scientists couple magnetization to supercond…

Scientists couple magnetization to superconductivity for quantum discoveries

Quantum computing promises to revolutionize the ways in which scientists can process and manipulate information. The physical and material underpinnings for quantum technologies are still being explored, and researchers continue to look for new ways in which information can be manipulated and exchanged at the quantum level.

In a recent study, scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have created a miniaturized chip-based superconducting circuit that couples quantum waves of magnetic spins called magnons to photons of equivalent energy. Through the development of this “on chip” approach that marries magnetism and superconductivity for manipulation of quantum information, this fundamental discovery could help to lay the foundation for future advancements in quantum computing.

Magnons emerge in magnetically ordered systems as excitations within a magnetic material that cause an oscillation of the magnetization directions at each atom in the material—a phenomenon called a spin wave. “You can think of it like having an array of compass needles that are all magnetically linked together,” said Argonne materials scientist Valentine Novosad, an author of the study. “If you kick one in a particular direction, it will cause a wave that propagates through the rest.”

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A novel graphene-matrix-assisted stabilizati…

A novel graphene-matrix-assisted stabilization method will help 2-D materials become a part of quantum computers

Scientists from Russia and Japan found a way of stabilizing two-dimensional copper oxide (CuO) materials by using graphene. Along with being the main candidates for spintronics applications, these materials may be used in forthcoming quantum computers. The results of the study were published in The Journal of Physical Chemistry C.

The family of 2-D materials has recently been joined by a new class, the monolayers of oxides and carbides of transition metals, which have been the subject of extensive theoretical and experimental research. These new materials are of great interest to scientists due to their unusual rectangular atomic structure and chemical and physical properties, and in particular, a unique 2-D rectangular copper oxide cell which does not exist in crystalline (3-D) form, as opposed to most of the 2-D materials, whether well-known or discovered lately, which have a lattice similar to that of their crystalline (3-D) counterparts. The main hindrance for practical use of monolayers is their low stability.

A group of scientists from MISiS, the Institute of Biochemical Physics of RAS (IBCP), Skoltech, and the National Institute for Materials Science in Japan (NIMS) discovered 2-D copper oxide materials with an unusual crystal structure inside the two-layer graphene matrix using experimental methods.

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Granular aluminum for future computers

Granular aluminum for future computers

Computers based on quantum mechanical principles can solve certain tasks particularly efficiently. Their information carriers, the so-called qubits, not only have the values “0” and “1,” but also states in between, called superposition states. However, maintaining such a state is difficult. Scientists at the Karlsruhe Institute of Technology (KIT) have now used granular aluminum (nicknamed grAl) for qubits and have shown that this superconducting material has great potential to overcome the previous limits of quantum hardware. The researchers report in the journal Nature Materials.

Quantum computers are considered the computers of the future. You can in principle process large amounts of data much quicker than with current classical computers. While classical computers perform one step at a time, quantum computers can be regarded as taking many steps in parallel, in so-called quantum parallelism. The information carrier for the quantum computer is the quantum bit, qubit in short. For qubits not only the states “0” and “1” are relevant, but also the states in between, the quantum mechanical superposition of states. Their processing is done according to quantum mechanical principles, such as entanglement, which preserves instant correlations between qubit states to arbitrary long distances.

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Virginia Tech researchers lead breakthrough in…

Virginia Tech researchers lead breakthrough in quantum computing

The large, error-correcting quantum computers envisioned today could be decades away, yet experts are vigorously trying to come up with ways to use existing and near-term quantum processors to solve useful problems despite limitations due to errors or “noise.”

[…]

A key envisioned use is simulating molecular properties. In the long run, this can lead to advances in materials improvement and drug discovery. But not with noisy calculations confusing the results.

Now, a team of Virginia Tech chemistry and physics researchers have advanced quantum simulation by devising an algorithm that can more efficiently calculate the properties of molecules on a noisy quantum computer. Virginia Tech College of Science faculty members Ed Barnes, Sophia Economou, and Nick Mayhall recently published a paper in Nature Communications detailing the advancement.

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Physicists have let light through the plane …

Physicists have let light through the plane of the world’s thinnest semiconductor crystal

In every modern microcircuit hidden inside a laptop or smartphone, you can see transistors—small semiconductor devices that control the flow of electric current, i.e. the flow of electrons. If we replace electrons with photons (elementary particles of light), then scientists will have the prospect of creating new computing systems that can process massive information flows at a speed close to the speed of light. At present, it is photons that are considered the best for transmitting information in quantum computers. These are still hypothetical computers that live according to the laws of the quantum world and are able to solve some problems more efficiently than the most powerful supercomputers.

Although there are no fundamental limits for creating quantum computers, scientists still have not chosen what material platform will be the most convenient and effective for implementing the idea of a quantum computer. Superconducting circuits, cold atoms, ions, defects in diamond and other systems now compete for being one chosen for the future quantum computer. It has become possible to put forward the semiconductor platform and two-dimensional crystals, specifically, thanks to scientists from: the University of Würzburg (Germany); the University of Southampton (United Kingdom); the University of Grenoble Alpes (France); the University of Arizona (USA); the Westlake university (China), the Ioffe Physical Technical Institute of the Russian Academy of Sciences; and St Petersburg University.

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Limitation exposed in promising quantum comput…

Limitation exposed in promising quantum computing material: Metallic surfaces no longer protected as topological insulators become thinner

Quantum computers promise to perform operations of great importance believed to be impossible for our technology today. Current computers process information via transistors carrying one of two units of information, either a 1 or a 0. Quantum computing is based on the quantum mechanical behavior of the logic unit. Each quantum unit, or “qubit,” can exist in a quantum superposition rather than taking discrete values. The biggest hurdles to quantum computing are the qubits themselves–it is an ongoing scientific challenge to create logic units robust enough to carry instructions without being impacted by the surrounding environment and resulting errors.

[…]

Physicists have theorized that a new type of material, called a three-dimensional (3-D) topological insulator (TI), could be a good candidate from which to create qubits that will be resilient from these errors and protected from losing their quantum information. This material has both an insulating interior and metallic top and bottom surfaces that conduct electricity. The most important property of 3-D topological insulators is that the conductive surfaces are predicted to be protected from the influence of the surroundings. Few studies exist that have experimentally tested how TIs behave in real life.

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Quantum photonics by serendipity

Quantum photonics by serendipity

A photonic chip with no less than 128 tunable components proves to be a true computing “Swiss army knife” with a variety of applications. During her research on measuring light wavelengths using this photonic chip, Caterina Taballione of the University of Twente came across yet another application serendipitously—by sending single photons through the system instead of continuous light, the optical components can perform quantum operations, as well. The same chip works as a photonic quantum processor.

Manipulating light on a chip is now possible on a very advanced level, especially using combinations of materials. Researchers can build optical waveguides with very low losses using silicon nitride, or very narrow laser light sources using indium phosphide. The chip Caterina Taballione is presenting in her thesis contains many components that can either split or combine the light in and from separate channels, similar to a rail yard. It also has ring-shaped resonators that can work as a filter. The strength lies in the fact that the components can be controlled from the outside, making the chip flexible and programmable. It also has applications in quantum photonics.

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Physicists use light waves to accelerate sup…

Physicists use light waves to accelerate supercurrents, enable ultrafast quantum computing

Jigang Wang patiently explained his latest discovery in quantum control that could lead to superfast computing based on quantum mechanics: He mentioned light-induced superconductivity without energy gap. He brought up forbidden supercurrent quantum beats. And he mentioned terahertz-speed symmetry breaking.

Then he backed up and clarified all that. After all, the quantum world of matter and energy at terahertz and nanometer scales – trillions of cycles per second and billionths of meters – is still a mystery to most of us.

“I like to study quantum control of superconductivity exceeding the gigahertz, or billions of cycles per second, bottleneck in current state-of-the-art quantum computation applications,” said Wang, a professor of physics and astronomy at Iowa State University whose research has been supported by the Army Research Office. “We’re using terahertz light as a control knob to accelerate supercurrents.”

Superconductivity is the movement of electricity through certain materials without resistance. It typically occurs at very, very cold temperatures. Think -400 Fahrenheit for “high-temperature” superconductors.

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Quantum world-first: Researchers reveal accu…

Quantum world-first: Researchers reveal accuracy of two-qubit calculations in silicon

For the first time ever, researchers have measured the fidelity – that is, the accuracy – of two-qubit logic operations in silicon, with highly promising results that will enable scaling up to a full-scale quantum processor.

The research, carried out by Professor Andrew Dzurak’s team in UNSW Engineering, was published today in the journal Nature.

The experiments were performed by Wister Huang, a final-year PhD student in Electrical Engineering, and Dr Henry Yang, a senior research fellow at UNSW.

“All quantum computations can be made up of one-qubit operations and two-qubit operations – they’re the central building blocks of quantum computing,” says Professor Dzurak.

“Once you’ve got those, you can perform any computation you want – but the accuracy of both operations needs to be very high.”

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Oregon scientists drill into white graphene to…

Oregon scientists drill into white graphene to create artificial atoms: Patterned on a microchip and working in ambient conditions, the atoms could lead to rapid advancements in new quantum-based technology

By drilling holes into a thin two-dimensional sheet of hexagonal boron nitride with a gallium-focused ion beam, University of Oregon scientists have created artificial atoms that generate single photons.

[…]

The artificial atoms – which work in air and at room temperature – may be a big step in efforts to develop all-optical quantum computing, said UO physicist Benjamín J. Alemán, principal investigator of a study published in the journal Nano Letters.

“Our work provides a source of single photons that could act as carriers of quantum information or as qubits. We’ve patterned these sources, creating as many as we want, where we want,” said Alemán, a member of the UO’s Material Science Institute and Center for Optical, Molecular, and Quantum Science. “We’d like to pattern these single photon emitters into circuits or networks on a microchip so they can talk to each other, or to other existing qubits, like solid-state spins or superconducting circuit qubits.”

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