Category: quantum physics – Page 433
Theoretical physicists at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) have demonstrated how the coupling between intense lasers, the motion of electrons, and their spin influences the emission of light on the ultrafast timescale.
Electrons, which are present in all kinds of matter, are charged particles and therefore react to the application of light. When an intense light field hits a solid, electrons experience a force, called the Lorentz force, that drives them and induces some exquisite dynamics reflecting the properties of the material. This, in turn, results in the emission of light by the electrons at various wavelengths, a well-known phenomenon called high-harmonic generation.
Exactly how the electrons move under the influence of the light field depends on a complex mixture of properties of the solid, including its symmetries, topology, and band structure, as well as the nature of the light pulse. Additionally, electrons are like spinning tops. They have a propensity to rotate either clockwise or counter-clockwise, a property called the “spin” of the electrons in quantum mechanics.
Simpler, faster, smaller, and cheaper chips are a key to low-power computing — even in AI.
RISC-V is taking off like a rocket.
In this video I discuss how RISC-V will reshape chip design industry.
#RISCV
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We all learn from early on that computers work with zeros and ones, also known as binary information. This approach has been so successful that computers now power everything from coffee machines to self-driving cars and it is hard to imagine a life without them.
Building on this success, today’s quantum computers are also designed with binary information processing in mind. “The building blocks of quantum computers, however, are more than just zeros and ones,” explains Martin Ringbauer, an experimental physicist from Innsbruck, Austria. “Restricting them to binary systems prevents these devices from living up to their true potential.”
The team led by Thomas Monz at the Department of Experimental Physics at the University of Innsbruck, now succeeded in developing a quantum computer that can perform arbitrary calculations with so-called quantum digits (qudits), thereby unlocking more computational power with fewer quantum particles. Their study is published in Nature Physics.
This mind-bending property offers a sought-after benefit: Information stored in the phase is far more protected against errors than with alternative setups currently used in quantum computers. As a result, the information can exist without getting garbled for much longer, an important milestone for making quantum computing viable, says study lead author Philipp Dumitrescu.
The approach’s use of an “extra” time dimension “is a completely different way of thinking about phases of matter,” says Dumitrescu, who worked on the project as a research fellow at the Flatiron Institute’s Center for Computational Quantum Physics in New York City. “I’ve been working on these theory ideas for over five years, and seeing them come actually to be realized in experiments is exciting.”
From its very inception quantum mechanics troubled physicists. It seemed to challenge our conception of reality and lead to apparent contradictions. One of the founders of quantum mechanics, Ernst Heisenberg, questioned whether the theory offered a description of reality at all. Others, like Niels Bohr, claimed that somehow human consciousness played a role in the theory. In this interview, Carlo Rovelli explains Heisenberg’s anti-realist motivations, clarifies the role of the “observer” in quantum mechanics, and articulates his relational interpretation of the theory, according to which reality is a network of interactions.
Carlo Rovelli will debate Sabine Hossenfelder and Eric Weinsten in the FREE IAI Live event, ‘Quantum Physics and the End of Reality’ on July 25th. Learn more here.
The founders of quantum mechanics were very uncomfortable with its results – famously Einstein thought it an incomplete theory and quipped “God doesn’t play dice”, and Schrödinger abandoned physics altogether for biology. What was so radically different about quantum mechanics than classical physics that caused such discomfort to its own creators?
Scientists have been grappling with the strangeness of quantum entanglement for decades, and it’s almost as mysterious in 2022 as it was when Einstein famously dubbed the phenomenon “spooky action at a distance” in 1947. An experiment in Germany that set a new entanglement distance record — with atoms rather than photons — could help shed some light on this quirk of the universe.
Entanglement was initially proposed in the early 20th century as a consequence of quantum mechanics, but many scientists of the day, even Einstein himself, considered it to be impossible. However, many of the counterintuitive predictions of quantum mechanics have been verified over the years, including entanglement. As we’ve seen in numerous experiments, it is possible for particles to be “entangled” such that properties like position, momentum, spin, and polarization can be shared between them. A change in one is immediately reflected in its twin.
Scientists believe entanglement could form the basis for future communication systems that are faster and more secure than what we use today — if you measure the state of one entangled partner, you automatically know the state of the other, and this could be used to transmit data. You just need to separate the entangled pair to make it useful, and researchers from Ludwig-Maximilians-University Munich (LMU) and Saarland University have pushed that range much farther in the new experiment.
Circa 2021 force field this can also shield the earth or cities.
The computational design of functional materials relies heavily on large-scale atomistic simulations. Such simulations are often problematic for conventional classical force fields, which require tedious and time-consuming parameterization of interaction parameters. The problem can be solved using a quantum mechanically derived force field (QMDFF)—a system-specific force field derived directly from the first-principles calculations. We present a computational approach for atomistic simulations of complex molecular systems, which include the treatment of chemical reactions with the empirical valence bond approach. The accuracy of the QMDFF is verified by comparison with the experimental properties of liquid solvents.