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Category: particle physics

Neutrons reveal magnetic signatures of chiral phonons

Physicists in China have uncovered new evidence that chiral phonons and magnons can interact strongly inside magnetic crystals. Using neutron spectroscopy, a team led by Song Bao at Nanjing University mapped magnetic signatures linked to chiral phonons in a ferrimagnetic material, revealing a previously elusive relationship between lattice vibrations and magnetic excitations. Reported in Physical Review Letters, the results could help researchers better understand how heat, sound and spin interact in quantum materials.

Phonons are collective vibrations of atoms in a crystal lattice which carry quantized packets of sound and heat through a solid. As quasiparticles, they behave somewhat like particles moving through the material and can interact with other excitations. In some cases, phonons also exhibit chirality: where some property of a particle differs from its mirror image.

For phonons, chirality arises when ions move in circular motions as the lattice vibrates, which imparts both an angular momentum and a tiny magnetic moment, which rotates in a plane perpendicular to the phonon’s direction of travel. Crucially, however, the phonon’s properties will vary depending on whether this rotation is clockwise or anticlockwise.

Electric field tunes vibrations to ease heat transfer

New research from the Department of Energy’s Oak Ridge National Laboratory, in collaboration with The Ohio State University and Amphenol Corporation, challenges conventional understanding about controlling heat flow in solid materials. The study, published in PRX Energy, shows that applying an electric field to a ceramic material changes how phonons (tiny vibrations that carry heat) behave.

Phonons with atoms moving along the field direction (poling direction) last longer than those with atoms moving perpendicular to the field. As a result, the material conducts heat almost three times more efficiently along the field direction than in perpendicular directions. This promising approach could lead to new solid-state devices that control heat flow in everyday technologies.

“Being able to control both how fast and in what manner heat flows could lead to devices that manage thermal energy far more efficiently,” said Puspa Upreti, an ORNL postdoctoral research associate.

Why Large Hadron Collider predictions can miss the mark, and a new way to fix it

Estimating things that exist is generally easy, but when it comes to estimating things that do not exist, it’s more difficult. This is something physicists from Poland and the UK are well aware of. To improve current simulations of high-energy particle collisions, they have developed a more accurate method for estimating the impact of calculations that are not performed.

Prediction can be difficult, especially when it comes to the future, as Niels Bohr—one of the fathers of quantum mechanics—once said. The fundamental problem with predicting the future lies in the simple fact that we just do not know it. A somewhat similar challenge arises in the calculations used to model high-energy particle collisions: For them to be useful, one must be able to estimate the impact of calculations that are not performed.

Physicists Matthew A. Lim from the University of Sussex in Brighton and Dr. Rene Poncelet from the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow have presented a new approach to this issue in the journal Physical Review D.

NA62 Collaboration refines measurement of rare particle decay

The NA62 Collaboration has dramatically reduced the uncertainty in its measurement of an extremely rare particle decay, in results just presented at the 2026 La Thuile conference.

The study of rare decays gives physicists the chance to probe the Standard Model of particle physics. Researchers can determine what is known as the branching ratio of a decay, which describes how many particles decay through a particular process as a fraction of the total number of decays that occur.

The branching ratio of the decay that the NA62 Collaboration has studied—the decay of a positively charged kaon into a positively charged pion and neutrino–antineutrino pair (written K+→π+νν)—can be predicted theoretically with a very high degree of precision. Thanks to this “theoretical cleanliness,” this particular kaon decay is extremely sensitive to new physics beyond the Standard Model but, with a predicted branching ratio of less than one in 10 billion, it is extremely rare and very challenging to observe.

How “Empty Space” Is Supercharging Atomically Thin Semiconductors

A single layer of atoms may seem too thin to meaningfully interact with light, yet materials like tungsten disulfide are reshaping what is possible in nanophotonics. Researchers have now found a way to dramatically strengthen these interactions. Atomically thin semiconductors such as tungsten dis

On the number of digital pictures Let’s switch from Go positions to digital pictures

There is an art project to display every possible picture. The project admits this will take a long time, because there are many possible pictures. But how many? We will assume the very common color model known as True Color, in which each pixel can be one of 224 ≅ 17 million distinct colors. The digital camera shown below left has 12 million pixels. We’ll also consider much smaller pictures: the array below middle, with 300 pixels, and the array below right with just 12 pixels. Shown are some of the possible pictures:

12,000,000 pixels 300 pixels 12 pixels.

Quiz: Which of these produces a number of pictures similar to the number of atoms in the universe?

Answer: An array of n pixels produces (17 million)n different pictures. (17 million)12 ≅ 1,086, so the tiny 12-pixel array produces a million times more pictures than the number of atoms in the universe!

How about the 300 pixel array? It can produce 102,167 pictures. You may think the number of atoms in the universe is big, but that’s just peanuts to the number of pictures in a 300-pixel array. And 12M pixels? 1,086,696,638 pictures. Fuggedaboutit!

So the number of possible pictures is really, really, really big. And the number of atoms in the universe is looking relatively small, at least as a number of combinations.

On counting combinations People often underestimate the number of combinations of things. I think there are two main reasons: Combinations of things are multiplicative, while collections of things are additive. If you see a line of 6 people, it is easy to visualize a line of 60 people—it is ten times longer. But even if you know that there are 720 different orderings (permutations) in which those 6 people can line up, there is no way you can visualize the number of orderings for 60 people, because it is—you guessed it—larger than the number of atoms in the universe. Big numbers are hard. Even with simple collections of things, it takes practice to get a real intuition for the difference between 6 million and 6 billion people. When it comes to combinations, growth is faster and therefore intuition fails earlier. Authors are sloppy. Doug Smith reports that the New York Times confused “million” and “billion” over a dozen times per year; other sources also make similar mistakes. See the book by Unix co-creator Brian Kernighan for more on this. So beware, and be sure to use some simple math to augment your intuition when dealing with combinations.

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