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Category: quantum physics – Page 632

Spin valve uses coupled quantum dots and tiny magnetic fields

Researchers in Switzerland and Italy have developed a new method for generating currents of spin-polarized electrons without the need for large external magnetic fields. This could enable the development of devices that are compatible with superconducting electronic components, paving the way for the next generation of highly efficient electronics.

Emerging in the 1980s, “spintronics” is dedicated to creating practical devices that exploit electron spin. Semiconductor-based spintronics systems have garnered particular interest because semiconductors can be integrated within modern-day electronics with the aim of improving the efficiency and storage capacity of devices. But to make useful spintronics devices, researchers must control and detect the spin state of electrons with a high level of accuracy.

One way of controlling electron spin current is a “spin valve”, which usually consists of a non-magnetic material sandwiched between ferromagnetic materials. Electrons in one spin state (say up) can propagate through the device, while spin-down electrons are reflected or scattered away. The result is a “spin polarized current” in which all electrons are either spin-up or all spin-down) – at least in principle.

Optical technique sorts nanodiamonds

A method of optically selecting and sorting nanoparticles according to their quantum mechanical properties has been developed by researchers in Japan. The method could prove a crucial tool for manufacturing nanostructures for quantum sensing, biological imaging and quantum information technology ( Sci. Adv. 7 eabd9551).

Scientists have several ways of manipulating and positioning tiny objects without touching them. Optical tweezers, for example, use a highly focused laser beam to generate optical forces that hold and move objects in the beam’s trajectory. However, such tweezers struggle to grasp nanoparticles because these tiny objects are much smaller than the wavelength of the laser light used.

Now, a team led by Hajime Ishihara of Osaka University and Keiji Sasaki at Hokkaido University has developed a way of using light to sort nanodiamonds. These are tiny pieces of semiconductor with very useful optoelectronic properties that derive from bulk diamond as well as certain defects such as nitrogen-vacancy (NV) centres.

Atomic quantum processors make their debut

Two research groups demonstrate quantum algorithms using neutral atoms as qubits. Tim Wogan reports.

The first quantum processors that use neutral atoms as qubits have been produced independently by two US-based groups. The result offers the possibility of building quantum computers that could be easier to scale up than current devices.

Two technologies have dominated quantum computing so far, but they are not without issues. Superconducting qubits must be constructed individually, making it nearly impossible to fabricate identical copies, so the probability of the output being correct is reduced – causing what is known as “gate fidelity”. Moreover, each qubit must be cooled close to absolute zero. Trapped ions, on the other hand, have the advantage that each ion is guaranteed to be indistinguishable by the laws of quantum mechanics. But while ions in a vacuum are relatively easy to isolate from thermal noise, they are strongly interacting and so require electric fields to move them around.

Time crystals: the search for a new phase of matter

Pedram Roushan, from Google’s Quantum AI team in California, describes this elusive form of matter – and how it could be simulated on the company’s Sycamore quantum processor.

With their enchanting beauty, crystalline solids have captivated us for centuries. Crystals, which range from snowflakes to diamonds, are made up of atoms or molecules that are regularly arranged in space. They have provided foundational insights that led to the development of the quantum theory of solids. Crystals have also helped develop a framework for understanding other spatially ordered phases, such as superconductors, liquid crystals and ferromagnets.

Periodic oscillations are another ubiquitous phenomenon. They appear at all scales, ranging from atomic oscillations to orbiting planets. For many years, we used them to mark the passage of time, and they even made us ponder the possibility of perpetual motion. What is common between these periodic patterns – either in space or time – is that they lead to systems with reduced symmetries. Without periodicity, any position in space, or any instance of time, is indistinguishable from any other. Periodicity breaks the translational symmetry of space or time.

Programmable photonic chip lights up quantum computing

Tight squeeze The Xanadu X8 quantum photonic processor used in the study. (Courtesy: Xanadu) Computers are made of chips, and in the future, some of those chips might use light as their main ingredient. Scientists from the Ontario, Canada-based…

Giant bacteria, Ca. Thiomargarita magnifica, have been found in Guadeloupe. They have organelles, DNA and measure one centimeter long.

The Next Generation Of IBM Quantum Computers

IBM is building accessible, scalable quantum computing by focusing on three pillars:

**· **Increasing qubit counts.

**· **Developing advanced quantum software that can abstract away infrastructure complexity and orchestrate quantum programs.

**· **Growing an ecosystem of quantum-ready enterprises, organizations, and communities.

The next step in IBM’s goals to build a frictionless development experience will be the release of Qiskit Runtime in 2022, which will allow developers to build workflows in the cloud, offering greater flexibility. Bringing a serverless approach to quantum computing will also provide the flexibility to distribute workloads intelligently and efficiently across quantum and classical systems.

To help speed the work of developers, IBM launched Qiskit Runtime primitives earlier this year. The primitives implement common quantum hardware queries used by algorithms to simplify quantum programming. In 2023, IBM plans to expand these primitives, as well as the capability to run on the next generation of parallelized quantum processors.

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J. Randall & S. Kalinin | Ready for Atomically Precise Manufacturing & Electron Microscopy

Foresight Molecular Machines Group.
Program & apply to join: https://foresight.org/molecular-machines/

John Randall.
Why the world is finally ready for Atomically Precise Manufacturing.

Sergei Kalinin.
Electron Microscopy: The Fab on a Beam.

John Randall is currently President/CEO at Zyvex Labs. Prior to Zyvex, John spent 15 years with Texas Instruments (TI) where he worked in high resolution processing for integrated circuits, MEMS, and quantum effect devices and also worked at MIT’s Lincoln Laboratory on ion beam and x-ray lithography. John is Executive VP at NanoRetina and currently lends his 30+ years of experience in micro-and nano-fabrication to his roles as.
Adjunct Professor at UT Dallas and Fellow of the AVS and IEEE.

Sergei Kalinin is a corporate fellow at the Center for Nanophase Materials.
Sciences (CNMS) at Oak Ridge National Laboratory. He is also a Joint Associate Professor at the Department of Materials Science and Engineering at the University of Tennessee-Knoxville. He is a recipient of the Blavatnik Award (2018) and the RMS medal for Scanning Probe Microscopy (2015).

Find a written summary of this talk here (including slides, notes and more):

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Silicon Quantum Computing announces world’s first quantum integrated circuit

After a Sydney-based firm built the world’s first atomic-scale quantum integrated circuit.

Sydney-based firm Silicon Quantum Computing (SQC) built the first integrated silicon quantum computer circuit manufactured at the atomic scale, in what has been touted as a “major breakthrough” on the road to quantum supremacy, a press statement reveals.

The atomic-scale integrated circuit, which functions as an analog quantum processor, may be SQC’s biggest milestone since it announced in 2012 that it had built the world’s first single-atom transistor.

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