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Category: quantum physics

Circa 2019

LONDON — A laboratory in Switzerland has found a way of using a laser to change and regulate the polarization, wavelength and intensity of light in “excitons” in 2D materials, creating the potential for a new generation of transistors with less energy loss and heat dissipation, opening up the potential for low-power quantum computing.

Excitons are created when an electron absorbs light and moves into a higher energy level, or “energy band” as it is called in solid quantum physics. This excited electron leaves behind an “electron hole” in its previous energy band. And because the electron has a negative charge and the hole a positive charge, the two are bound together by an electrostatic force called a Coulomb force. It’s this electron-electron hole pair that is referred to as an exciton.

Scientists from EPFL’s Laboratory of Nanoscale Electronics and Structures (LANES) had already developed a method to control exciton flows at room temperature last year. In the latest development, they have discovered new properties of these quasiparticles that can lead to more energy-efficient electronic devices and have found a way to control some of the properties and change the polarization of the light they generate. The scientists’ discovery forms part of a relatively new field of research called valleytronics and has just been published in Nature Photonics.

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Circa 2012

Quantum ground-state problems are computationally hard problems for general many-body Hamiltonians; there is no classical or quantum algorithm known to be able to solve them efficiently. Nevertheless, if a trial wavefunction approximating the ground state is available, as often happens for many problems in physics and chemistry, a quantum computer could employ this trial wavefunction to project the ground state by means of the phase estimation algorithm (PEA). We performed an experimental realization of this idea by implementing a variational-wavefunction approach to solve the ground-state problem of the Heisenberg spin model with an NMR quantum simulator. Our iterative phase estimation procedure yields a high accuracy for the eigenenergies (to the 10–5 decimal digit).

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Isaac Newton’s groundbreaking scientific productivity while isolated from the spread of bubonic plague is legendary. University of California San Diego physicists can now claim a stake in the annals of pandemic-driven science.

A team of UC San Diego researchers and colleagues at Purdue University have now simulated the foundation of new types of artificial intelligence computing devices that mimic brain functions, an achievement that resulted from the COVID-19 pandemic lockdown. By combining new supercomputing materials with specialized oxides, the researchers successfully demonstrated the backbone of networks of circuits and devices that mirror the connectivity of neurons and synapses in biologically based neural networks.

The simulations are described in the Proceedings of the National Academy of Sciences (PNAS).

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The patent in question is for a system that would use quantum teleportation in order to boost a quantum computer’s reliability, while at the same time reducing the number of qubits required for a given calculation. This “teleportation” technology would help solve scaling issues and calculation errors that arise from system instability.

One of the main issues behind quantum development is once you start pushing the pedal to the metal, there are major issues when it comes to scalability and stability. Quantum computing is far different to the 0s and 1s of traditional technology, so AMD’s new teleportation patent is quite an important step towards solving that issue.

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A new interpretation of quantum mechanics sees agents as playing an active role in the creation of reality. Blake Stacey outlines the case for QBism and its radical potential.

The pandemic shut down our university when I was in the middle of giving a lecture. We had been anticipating the possibility for a few days, but it was still impeccable timing. I finished my spiel, out came the phones, and suddenly we weren’t going to see each other post-spring break after all. For the rest of the term, I did what so many teachers found themselves doing: gamely trying to soldier on. I scrounged and borrowed a whiteboard, easel and webcam, set myself up in the nicest light the house had to offer, and did my best to convey graduate-level physics to an audience of tiny rectangles. And like so many other teachers, I learned there’s nothing like a radical change of circumstances for driving one to re-evaluate what the essential ideas of a subject must be.

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Isaac Nape, an emerging South African talent in the study of quantum optics, is part of a crack team of Wits physicists who led an international study that revealed the hidden structures of quantum entangled states. The study was published in the renowned scientific journal, Nature Communications, on Friday, 27 August 2021.

Nape is pursuing his Ph.D. at Wits University and focuses on harnessing structured for high dimensional information encoding and decoding for use in .

Earlier this year he scooped up two awards at the South African Institute of Physics (SAIP) conference to add to his growing collection of accolades in the field of optics and photonics. He won the award for “Best Ph.D. oral presentation in applied physics,” and jointly won the award for “Best Ph.D. oral presentation in photonics.”

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