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Category: computing – Page 206

IBM introduces introducing two new metrics — error per layered gate (EPLG) and CLOPSh — to fully encapsulate the performance of 100+ qubit processors powering this utility-scale era.

Layer fidelity provides a benchmark that encapsulates the entire processor’s ability to run circuits while revealing information about individual qubits, gates, and crosstalk. It expands on a well-established way to benchmark quantum computers, called randomized benchmarking. With randomized benchmarking, we add a set of randomized Clifford group gates (that’s the basic set of gates we use: X, Y, Z, H, SX, CNOT, ECR, CZ, etc.) to the circuit, then run an operation that we know, mathematically, should represent the inverse of the sequence of operations that precede it.

If any of the qubits do not return to their original state by the inverse operation upon measurement, then we know there was an error. We extract a number from this experiment by repeating it multiple times with more and more random gates, plotting on a graph how the errors increase with more gates, fitting an exponential decay to the plot, and using that line to calculate a number between 0 and 1, called the fidelity.

So, layer fidelity gives us a way to combine randomized benchmarking data for larger circuits to tell us things about the whole processor and its subsets of qubits.

Continue reading “Updating how we measure quantum quality and speed” | >

Researchers in China have produced a phenomenon known as the giant skyrmion topological Hall effect in a two-dimensional material using only a small amount of current to manipulate the skyrmions responsible for it. The finding, which a team at Huazhong University of Science and Technology in Hubei observed in a ferromagnetic crystal discovered in 2022, comes about thanks to an electronic spin interaction known to stabilize skyrmions. Since the effect was apparent at a wide range of temperatures, including room temperature, it could prove useful for developing two-dimensional topological and spintronic devices such as racetrack memory, logic gates and spin nano-oscillators.

Skyrmions are quasiparticles with a vortex-like structure, and they exist in many materials, notably magnetic thin films and multilayers. They are robust to external perturbations, and at just tens of nanometres across, they are much smaller than the magnetic domains used to encode data in today’s hard disks. That makes them ideal building blocks for future data storage technologies such as “racetrack” memories.

Skyrmions can generally be identified in a material by spotting unusual features (for example, abnormal resistivity) in the Hall effect, which occurs when electrons flow through a conductor in the presence of an applied magnetic field. The magnetic field exerts a sideways force on the electrons, leading to a voltage difference in the conductor that is proportional to the strength of the field. If the conductor has an internal magnetic field or magnetic spin texture, like a skyrmion does, this also affects the electrons. In these circumstances, the Hall effect is known as the skyrmion topological Hall effect (THE).

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Virtual reality, or VR, is not just for fun-filled video games and other visual entertainment. This technology, involving a computer-generated environment with objects that seem real, has found many scientific and educational applications as well.

Sean Preins, a doctoral student in the Department of Physics and Astronomy at the University of California, Riverside, has created a VR application called VIRTUE, for “Virtual Interactive Reality Toolkit for Understanding the EIC,” that is a game changer in how particle and nuclear physics data can be seen.

Made publicly available on Christmas Day, VIRTUE can be used to visualize experiments and simulated data from the upcoming Electron-Ion Collider, or EIC, a planned major new nuclear physics research facility at Brookhaven National Lab in Upton, New York. EIC will explore mysteries of the “strong force” that binds the atomic nucleus together. Electrons and ions, sped up to almost the speed of light, will collide with one another in the EIC.

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The company announces its latest huge chip — but will now focus on developing smaller chips with a fresh approach to ‘error correction’

The second-largest quantum computing chip won’t be fitted into IBM’s next-generation System Two quantum computer. Instead, it will use three smaller 133-qubit chips with a much lower error rate.

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Future quantum computers are expected to revolutionize problem-solving in various fields, such as creating sustainable materials, developing new medications, and unraveling complex issues in fundamental physics. However, these pioneering quantum systems are currently more error-prone than the classical computers we use today. Wouldn’t it be nice if researchers could just take out a special quantum eraser and get rid of the mistakes?

Reporting in the journal Nature, a group of researchers led by Caltech is among the first to demonstrate a type of quantum eraser. The physicists show that they can pinpoint and correct for mistakes in quantum computing systems known as “erasure” errors.

“It’s normally very hard to detect errors in quantum computers, because just the act of looking for errors causes more to occur,” says Adam Shaw, co-lead author of the new study and a graduate student in the laboratory of Manuel Endres, a professor of physics at Caltech. “But we show that with some careful control, we can precisely locate and erase certain errors without consequence, which is where the name erasure comes from.”

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Researchers call it the ‘Holy Grail’ for physicists and engineers.

A group of researchers, led by Professor Chan Chi-hou from the City University of Hong Kong, created a special antenna that can control all five important aspects of electromagnetic waves using computer software.

The antenna, which they have named ’microwave universal metasurface antenna,’ is capable of dynamically, simultaneously, independently, and precisely manipulating all the essential properties of electromagnetic waves through software control.

“A universal component capable of manipulating all the fundamental wave properties is the Holy Grail for physicists and engineers,” said Professor Chan.

Continue reading “Hong Kong develops world’s first antenna for ultra-secure 6G” | >