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Can thermal noise train a computer? A new framework points to low-power AI

What if the thermal noise that hinders the efficiency of both classical and quantum computers could, instead, be used as a power source? What if computers could make use of the noise instead of suppressing or overcoming it? These are the goals of a relatively new branch of computing known as thermodynamic computing. A collaboration between researchers at the Molecular Foundry and the National Energy Research Scientific Computing Center (NERSC), both U.S. Department of Energy (DOE) user facilities located at Lawrence Berkeley National Laboratory (Berkeley Lab), is bringing them closer to reality.

In a paper published in Nature Communications, the researchers have proposed a design and training framework for a type of thermodynamic computer that mimics a neural network, which could drastically reduce the energy requirements of machine learning.

Modern computing requires energy: a single Google search, for example, consumes enough energy to power a six-watt LED for three minutes. This is partly because computers must contend with thermal noise—that is, the vibration of charge carriers, mostly electrons, within electronically conductive materials. In classical computers, even the smallest devices, such as transistors and gates, operate at energy scales thousands of times larger than that of this vibration.

Scientists create a hexagonal diamond that could be even harder than the real thing

To misquote a famous song, “Diamonds are industry’s best friend.” Cubic diamond is the hardest mineral on Earth and is used in everything from precision cutting tools to high-performance semiconductors as well as expensive jewelry. But there is a rare and potentially tougher form called hexagonal diamond (HD), which has long been the subject of theories and debate over its actual existence. But now researchers from China claim to have created this elusive form of carbon in the lab.

Hexagonal diamond (also known as lonsdaleite) is usually found at sites of meteorite impacts. But because the quantities are so small and mixed with minerals, some scientists doubted it was a distinct material. In a paper published in the journal Nature, researchers describe how they made a bulk piece of pure HD using extreme pressure and heat.

New LVK catalog adds 128 gravitational-wave candidates, more than doubling detections

When the densest objects in the universe collide and merge, the violence sets off ripples, in the form of gravitational waves, that reverberate across space and time, over hundreds of millions and even billions of years. By the time they pass through Earth, such cosmic ripples are barely discernible.

And yet, scientists are able to detect them, thanks to a global network of gravitational-wave observatories: the U.S.-based National Science Foundation Laser Interferometer Gravitational-Wave Observatory (NSF LIGO), the Virgo interferometer in Italy, and the Kamioka Gravitational Wave Detector (KAGRA) in Japan. Together, the observatories “listen” for faint wobbles in the gravitational field that could have come from far-off astrophysical smash-ups.

Now the LIGO-Virgo-KAGRA (LVK) Collaboration is publishing its latest compilation of gravitational-wave detections, presented in a forthcoming special issue of Astrophysical Journal Letters. From the findings, it appears that the universe is echoing all over with a kaleidoscope of cosmic collisions.

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.

Missing technosignatures? Turbulent plasma may blur ultra-narrow signals before they leave their home star systems

A new study by researchers at the SETI Institute suggests that stellar “space weather” could make radio signals from extraterrestrial intelligence harder to detect. Stellar activity and plasma turbulence near a transmitting planet can broaden an otherwise ultra-narrow signal, spreading its power across more frequencies and making it more difficult to detect in traditional narrowband searches. The paper is published in The Astrophysical Journal.

For decades, many SETI experiments have focused on identifying spikes in frequency—signals unlikely to be produced by natural astrophysical processes. But the new research highlights an overlooked complication: even if an extraterrestrial transmitter produces a perfectly narrow signal, it may not remain narrow by the time it leaves its home system.

In most technosignature searches, scientists account for distortions that happen as radio waves travel across interstellar space. This study focuses on what can happen closer to the source. Plasma density fluctuations in stellar winds, as well as occasional eruptive events such as coronal mass ejections, can distort radio waves near their point of origin, effectively “smearing” the signal’s frequency and reducing the peak strength that search pipelines rely on.

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.

Researchers create a never-before-seen molecule and prove its exotic nature with quantum computing

An international team of scientists from IBM, The University of Manchester, Oxford University, ETH Zurich, EPFL and the University of Regensburg have created and characterized a molecule unlike any previously known—one whose electrons travel through its structure in a corkscrew-like pattern that fundamentally alters its chemical behavior. The work appears in Science.

This is the first experimental observation of a half-Möbius electronic topology in a single molecule. To the scientists’ knowledge, a molecule with such topology has never before been synthesized, observed, or even formally predicted.

Understanding this molecule’s behavior at the electronic structure level required something equally fundamental: a high-fidelity quantum computing simulation. The discovery advances science on two fronts. For chemistry, it demonstrates that electronic topology—the property governing how electrons move through a molecule—can be deliberately engineered, not merely found in nature.

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.

Polymers that crawl like worms: How materials can develop direction without being told where to go

Researchers at the University of Vienna have uncovered a surprising phenomenon: polymer chains with segments that simply fluctuate at different intensities can spontaneously develop directional, persistent motion when densely packed—even though nothing in the system points them in any particular direction. This “entropic tug of war,” driven by fundamental physical constraints, could help explain how DNA organizes and moves inside living cells and may lead to new materials. The study is published in Physical Review X.

“Think of a chain threaded through a dense forest of trees, which represent obstacles posed by the other chains in the system. One end of the chain is being shaken much more vigorously than the other,” explains lead author Jan Smrek from the Faculty of Physics at the University of Vienna. “You might expect it to just wiggle randomly in place. But we found that because the chain has to find its way by going in-between the trees, the difference in shaking intensity creates an imbalance that actually propels the entire chain forward through the forest.”

This analogy can be conferred to a polymer, a large molecule consisting of many units linked together in a long chain, such as DNA. The Viennese research team—Adam Höfler, Iurii Chubak, Christos Likos and Jan Smrek—used computer simulations and analytical theory to show that this directed motion arises purely from topological constraints. When polymer chains are entangled and cannot pass through each other, segments with stronger fluctuations generate larger entropic forces. This creates an imbalance that pushes the entire chain forward along its own contour, with the stronger fluctuating part acting as the “head of the snake” moving through the forest of obstacles.

Molecular ‘catapult’ fires electrons at the limits of physics

Electrons can be “kicked across” solar materials at almost the fastest speed nature allows, scientists have discovered, challenging long-held theories about how solar energy systems work. The finding could help researchers design more efficient ways of harvesting sunlight and converting it into electricity. The research is published in Nature Communications.

In experiments capturing events lasting just 18 femtoseconds —less than 20 quadrillionths of a second—researchers at the University of Cambridge observed charge separation happening within a single molecular vibration.

“We deliberately designed a system that—according to conventional theory—should not have transferred charge this fast,” said Dr. Pratyush Ghosh, Research Fellow, at St John’s College, Cambridge, and first author of the study. “By conventional design rules, this system should have been slow, and that’s what makes the result so striking.

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