Archive for the ‘quantum physics’ category: Page 5

Jun 28, 2022

Taking quantum control of life’s building blocks

Posted by in categories: alien life, chemistry, quantum physics

Life (as we know it) is based on carbon. Despite its ubiquity, this important element still holds plenty of secrets, on earth and in the heavens above us. For example, astrophysicists like Columbia’s Daniel Wolf Savin who study interstellar clouds want to understand how the chemicals, including carbon, swirling within these nebulous aggregations of gas and dust form the stars and planets that dot our universe and give rise to organic life.

Jun 28, 2022

Quantum Circuit Uses Just A Few Atoms

Posted by in categories: computing, particle physics, quantum physics

Researchers at the University of New South Wales and a startup company, Silicon Quantum Computing, published results of their quantum dot experiments. The circuits use up to 10 carbon-based quantum dots on a silicon substrate. Metal gates control the flow of electrons. The paper appears in Nature and you can download the full paper from there.

What’s new about this is that the dots are precisely arranged to simulate an organic compound, polyacetylene. This allowed researchers to model the actual molecule. Simulating molecules is important in the study of exotic matter phases, such as superconductivity. The interaction of particles inside, for example, a crystalline structure is difficult to simulate using conventional methods. By building a model using quantum techniques on the same scale and with the same topology as the molecule in question, simulation is simplified.

The SSH (Su-Schreffer-Heeger) model describes a single electron moving along a one-dimensional lattice with staggered tunnel couplings. At least, that’s what the paper says and we have to believe it. Creating such a model for simple systems has been feasible, but for a “many body” problem, conventional computing just isn’t up to the task. Currently, the 10 dot model is right at the limit of what a conventional computer can simulate reasonably. The team plans to build a 20 dot circuit that would allow for unique simulations not feasible with classic computing tech.

Jun 28, 2022

2D interfaces in future transistors may not be as flat as previously thought

Posted by in categories: computing, mobile phones, particle physics, quantum physics

Transistors are the building blocks of modern electronics, used in everything from televisions to laptops. As transistors have gotten smaller and more compact, so have electronics, which is why your cell phone is a super powerful computer that fits in the palm of your hand.

But there’s a scaling problem: Transistors are now so small that they are difficult to turn off. A key device element is the channel that charge carriers (such as electrons) travel across between electrodes. If that channel gets too short, allow electrons to effectively jump from one side to another even when they shouldn’t.

One way to get past this sizing roadblock is to use layers of 2D materials—which are only a single atom thick—as the channel. Atomically thin channels can help enable even smaller transistors by making it harder for the electrons to jump between electrodes. One well-known example of a 2D material is graphene, whose discoverers won the Nobel Prize in Physics in 2010. But there are other 2D materials, and many believe they are the future of transistors, with the promise of scaling channel thickness down from its current 3D limit of a few nanometers (nm, billionths of a meter) to less than a single nanometer thickness.

Jun 28, 2022

Spin valve uses coupled quantum dots and tiny magnetic fields

Posted by in categories: particle physics, quantum physics

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.

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Jun 28, 2022

Optical technique sorts nanodiamonds

Posted by in categories: biological, nanotechnology, quantum physics

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.

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Jun 28, 2022

Atomic quantum processors make their debut

Posted by in categories: computing, information science, particle physics, quantum physics

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.

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Jun 28, 2022

Time crystals: the search for a new phase of matter

Posted by in categories: particle physics, quantum physics, robotics/AI, space

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.

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Jun 28, 2022

Programmable photonic chip lights up quantum computing

Posted by in categories: computing, quantum physics

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.

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Jun 28, 2022

Demonstration of fault-tolerant universal quantum gate operations

Posted by in categories: computing, quantum physics

Error free quantum computing 😀

A fault-tolerant, universal set of single-and two-qubit quantum gates is demonstrated between two instances of the seven-qubit colour code in a trapped-ion quantum computer.

Jun 26, 2022

The Next Generation Of IBM Quantum Computers

Posted by in categories: computing, information science, quantum physics

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.

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