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One of the most exciting applications of quantum computers will be to direct their gaze inwards, at the very quantum rules that make them tick. Quantum computers can be used to simulate quantum physics itself, and perhaps even explore realms that don’t exist anywhere in nature.

But even in the absence of a fully functional, large-scale quantum computer, physicists can use a quantum system they can easily control to emulate a more complicated or less accessible one. Ultracold atoms—atoms that are cooled to temperatures just a tad above absolute zero—are a leading platform for quantum simulation. These atoms can be controlled with laser beams and magnetic fields, and coaxed into performing a quantum dance routine choreographed by an experimenter. It’s also fairly easy to peer into their quantum nature using high-resolution imaging to extract information after—or while—they complete their steps.

Now, researchers at JQI and the NSF Quantum Leap Challenge Institute for Robust Quantum Simulation (RQS), led by former JQI postdoctoral fellow Mingwu Lu and graduate student Graham Reid, have coached their ultracold atoms to do a new dance, adding to the growing toolkit of quantum simulation. In a pair of studies, they’ve bent their atoms out of shape, winding their quantum mechanical spins around in both space and time before tying them off to create a kind of space-time quantum pretzel.

Destroying an Earth-killing asteroid is not always possible, here’s what we can do instead.

Do you know what size asteroid would be enough to end all life on Earth? According to the experts at NASA, a space rock only 96 km wide can do the job.

Continue reading “Dust particles from an asteroid could save Earth from doomsday” »

Paris-based quantum computing startup PASQAL announced today it has raised €100 million in a Series B funding round, led by a new investor, Singapore-based Temasek. It was joined by the European Innovation Council (EIC) Fund, Wa’ed Ventures and Bpifrance, through its Large Venture Fund and existing investors Quantonation, the Defense Innovation Fund, Daphni and Eni Next. This brings PASQAL’s total funding to date to more than €140 million.

Founded in 2019 as a spin-off from Institut d’Optique, PASQAL develops quantum processors based on ordered neutral atoms in 2D and 3D arrays. Physics Today.

PASQAL’s technology is based on research conducted by the winner of the 2022 Nobel Prize in Physics, and it plans to deliver major commercial advantages over classical computers by 2024.

Continue reading “A ‘Dark Horse’ In The Quantum Computing Race Raises €100 Million” »

Dark matter remains one of the greatest mysteries of modern physics. It is clear that it must exist, because without dark matter, for example, the motion of galaxies cannot be explained. But it has never been possible to detect dark matter in an experiment.

Currently, there are many proposals for new experiments: They aim to detect dark matter directly via its scattering from the constituents of the atomic nuclei of a detection medium, i.e., protons and neutrons.

A team of researchers—Robert McGehee and Aaron Pierce of the University of Michigan and Gilly Elor of Johannes Gutenberg University of Mainz in Germany—has now proposed a new candidate for dark matter: HYPER, or “HighlY Interactive ParticlE Relics.”

Physicists at the University of Bonn have experimentally proven that an important theorem of statistical physics applies to so-called “Bose-Einstein condensates.” Their results now make it possible to measure certain properties of the quantum “superparticles” and deduce system characteristics that would otherwise be difficult to observe. The study has now been published in Physical Review Letters.

Suppose in front of you there is a container filled with an unknown liquid. Your goal is to find out by how much the particles in it (atoms or molecules) move back and forth randomly due to their thermal energy. However, you do not have a microscope with which you could visualize these position fluctuations known as “Brownian motion”.

It turns out you do not need that at all: You can also simply tie an object to a string and pull it through the liquid. The more force you have to apply, the more viscous your liquid. And the more viscous it is, the lesser the particles in the liquid change their position on average. The viscosity at a given temperature can therefore be used to predict the extent of the fluctuations.

Researchers from the Chinese Academy of Sciences’ Institute of Modern Physics and their collaborators have identified the most significant isospin mixing observed in beta-decay experiments, directly challenging our current understanding of the nuclear force. The findings were featured as an Editors’ Suggestion in the journal Physical Review Letters.

In 1932, Werner Heisenberg, a Nobel Prize laureate, introduced the idea of isospin to explain the symmetry in atomic nuclei resulting from the similar properties of protons and neutrons. Isospin symmetry is still widely accepted today.

However, isospin symmetry is not strictly conserved due to proton-neutron mass difference, Coulomb interaction, and charge-dependent aspects of nuclear force. Such asymmetry leads to fragmentation of the allowed Fermi transition to many states via strong isospin mixing, instead of being constrained to one state in β decay.

Researchers report a new, highly unusual, structured-light family of 3D topological solitons, the photonic hopfions, where the topological textures and topological numbers can be freely and independently tuned.

We can frequently find in our daily lives a localized wave structure that maintains its shape upon propagation—picture a smoke ring flying in the air. Similar stable structures have been studied in various research fields and can be found in magnets, nuclear systems, and particle physics. In contrast to a ring of smoke, they can be made resilient to perturbations. This is known in mathematics and physics as topological protection.

A typical example is the nanoscale hurricane-like texture of a magnetic field in magnetic thin films, behaving as particles—that is, not changing their shape—called skyrmions. Similar doughnut-shaped (or toroidal) patterns in 3D space, visualizing complex spatial distributions of various properties of a wave, are called hopfions. Achieving such structures with light waves is very elusive.

Patreon: https://www.patreon.com/seanmcarroll.
Blog post with audio player, show notes, and transcript: https://www.preposterousuniverse.com/podcast/2022/02/07/183-…e-physics/

Modern particle physics is a victim of its own success. We have extremely good theories — so good that it’s hard to know exactly how to move beyond them, since they agree with all the experiments. Yet, there are strong indications from theoretical considerations and cosmological data that we need to do better. But the leading contenders, especially supersymmetry, haven’t yet shown up in our experiments, leading some to wonder whether anthropic selection is a better answer. Michael Dine gives us an expert’s survey of the current situation, with pointers to what might come next.

Continue reading “Mindscape 183 | Michael Dine on Supersymmetry, Anthropics, and the Future of Particle Physics” »

I posted about Japan releasing radioactive water, and thought it was a bad idea, because of this MIT revelation.

Nuclear power continues to expand globally, propelled, in part, by the fact that it produces few greenhouse gas emissions while providing steady power output. But along with that expansion comes an increased need for dealing with the large volumes of water used for cooling these plants, which becomes contaminated with radioactive isotopes that require special long-term disposal.

Now, a method developed at MIT provides a way of substantially reducing the volume of contaminated water that needs to be disposed of, instead concentrating the contaminants and allowing the rest of the water to be recycled through the plant’s cooling system. The proposed system is described in the journal Environmental Science and Technology, in a paper by graduate student Mohammad Alkhadra, professor of chemical engineering Martin Bazant, and three others.

Continue reading “A new way to remove contaminants from nuclear wastewater” »