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Category: particle physics – Page 4

Attosecond X-ray method maps early electron motions that trigger chemical reactions

All chemistry starts with a push from electrons. In the early moments of a chemical reaction, it’s the movement of electrons that initiates the breaking of old chemical bonds and forging of new ones, transforming one molecule into another.

When an electron is removed from a molecule faster than the molecule can react—called “impulsive ionization”—the other electrons in the molecule enter excited quantum states that evolve on ultrafast timescales. Scientists have long sought to map the ultrasmall, ultrafast electronic motions behind chemical reactions on their natural timescales.

Now, researchers at the Department of Energy’s SLAC National Accelerator Laboratory have created a movie of early electron motion in an impulsively excited molecule. Each frame captures changes happening in mere attoseconds, just billionths of a billionth of a second.

‘Spooky’ particles transit DC suburbs, a step toward a quantum network

In early 2025, special signals wended their way through a fiber-optic highway strung above the streets and sidewalks of the Maryland suburbs. The arrival of those signals at their destination marks a significant step toward a long-held dream of building a “quantum network.” Researchers believe that this emerging technology could someday link quantum devices in ways that supercharge scientific research, enable ultrasecure communications and boost the power of future quantum computers.

National Institute of Standards and Technology (NIST) researchers and collaborators reported this advance in the Journal of Optical Communications and Networking.

A temperature dial for more realistic quantum simulations

Scientists from Rice University in the U.S. have developed a way to precisely tune the temperature inside a trapped-ion simulator. The breakthrough means they will be able to run quantum simulations at precise temperatures that better reflect real-world conditions.

Trapped-ion simulators are quantum devices that isolate charged particles inside a sealed vacuum chamber, using electric fields to hold them in place. They mimic and study complex quantum systems, such as chemical reactions or exotic materials, that are too difficult for ordinary computers to calculate.

Temperatures inside these devices are typically kept as close as possible to absolute zero so that thermal motion does not disrupt calculations or cause errors. But researchers lacked a suitable way to set the temperature without accidentally changing how fast the system loses energy. This meant that studies were mostly stuck using absolute zero or uncontrolled high temperatures.

New approach to cleaning the inner walls of a fusion system removes another obstacle to near-endless energy

Fusion systems need inner walls that can withstand extreme heat. One promising solution uses liquid lithium to protect the walls, held like water in a sponge made of the exceptionally strong metal tungsten. An advanced manufacturing process can be used to make tungsten into sponge-like wall tiles with lots of pores for flowing liquid lithium. But this process also leaves the tungsten contaminated with other materials, such as carbon, oxygen or nitrogen.

When exposed to liquid lithium, the carbon and oxygen react to form solids that can plug the holes in the tungsten, preventing the lithium from flowing properly. Even if the tungsten were cleaned at the end of the manufacturing process, it would become recontaminated when the tiles are exposed to air during installation.

Now researchers from the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL), Princeton University and Pennsylvania State University have found a clever way to clean those tiles after they are installed and sealed inside the fusion system—in vacuum chambers from which the air has been removed. The advance, which uses heat combined with particles from a neon plasma to knock contaminants out of tiles, could help future fusion systems run better with liquid lithium.

Molecular orbitals imaged in 3D, opening path to femtosecond videos

One of the most famous and intriguing results of quantum mechanics is the finding that fundamental particles, such as electrons, cannot be pinned down to one single location. Instead, a particle is described by its “wavefunction,” which allows researchers to derive probability distributions—a sort of mathematical map that shows the possibilities—of fundamental properties such as its position and momentum. In particular, the electron wavefunctions within a molecule, known as “molecular orbitals,” carry information about how the molecule interacts with its surroundings. For example, they show how it may absorb light or how a chemical reaction might take place.

As a consequence, knowledge of the complete three-dimensional wavefunction is highly desirable, but imaging the wavefunction has proven to be a major experimental challenge. An interdisciplinary research team at the University of Göttingen has now managed to image the three-dimensional wavefunction of a nanometer-sized organic molecule. They overcame the limitations by combining state-of-the-art photoelectron spectroscopy with powerful mathematical algorithms. The results are published in Nature Communications.

First measurement of antineutrinos from spent nuclear fuel confirms emissions persist after reactor shutdown

Even when the lights go out and nuclear reactors are turned off, the story inside the reactor core still has a great deal to tell. Radioactive, long-lived fission products continue to decay for months or even years, producing a faint flux of a specific type of particle known as antineutrinos. (Anti)neutrinos are the lightest and most elusive known particles in the universe, allowing them to escape unhindered from both the reactor and the surrounding shielding.

Researchers in the Double Chooz collaboration have now measured this residual antineutrino emission for the first time. The study, which was published in Physical Review Letters, was led by Anthony Onillon and Thierry Lasserre from the Max-Planck-Institut für Kernphysik (MPIK) in Heidelberg, Germany.

The results demonstrate that antineutrino detectors can probe nuclear reactors even during shutdown periods, opening new perspectives for reactor monitoring, nuclear safety and safeguards.

Quantum fluid reveals hidden states that can be switched with a magnetic field

Bose-Einstein condensates (BECs) are often described as a “fifth state of matter”: a quantum state in which many particles lose their individual identities and behave as one collective object. For more than 60 years, researchers have sought to create such condensates from excitons—electron-hole pairs—as a solid-state route to macroscopic quantum coherence, which is useful for quantum technologies. This has been difficult to realize in controllable semiconductor devices because optically generated excitons have very short lifetimes of around a billionth of a second, and BECs are normally attained with ultracold gases in a vacuum.

But now, a team led by Lawrence Berkeley National Laboratory (Berkeley Lab) has observed a tunable BEC of excitons at high temperature in an atomically thin semiconductor. The findings, published in Nature, reveal not only that the excitons form a BEC but also that the condensate has an internal structure that can be switched by a magnetic field.

The work enables a new platform for studying quantum fluids in solid materials. (A quantum fluid is an exotic state of matter in which gases of electrons or other particles behave collectively like a fluid.) It also has implications for future quantum simulations, coherent optoelectronics in next-generation telecommunications and computing, and exciton-based devices enabling faster, more efficient computing.

Scientists Discover What Makes Hydrogen Go Quantum

The symmetry of vanadium’s crystal structure acts as a switch for hydrogen’s quantum behavior.

Inside a vanadium crystal, hydrogen can travel in two very different ways. It may move as a conventional particle that needs enough energy to jump between locations, or behave like a quantum wave that passes through barriers. Researchers have now identified the structural change that determines which route it takes.

The finding could matter as demand grows for materials that can safely store and transport hydrogen as a source of cleaner energy. Vanadium is a promising candidate because it absorbs hydrogen readily and allows the atoms to move through its crystal lattice, although the reason for their changing behavior had remained uncertain.

Scientists Discover Extreme Acceleration Inside a Nuclear Fireball

Simulations reveal some of the strongest accelerations ever produced on Earth, opening new avenues for QCD research.

When atomic nuclei smash together at almost the speed of light, their internal matter briefly transforms into quark–gluon plasma, an extremely hot fluid in which quarks and gluons move freely.

Scientists have closely examined the plasma’s intense rotation and electromagnetic fields, but the acceleration driving its rapid expansion has received far less attention. In hydrodynamics, however, acceleration is as fundamental as vorticity, just as electric and magnetic fields are paired in electromagnetism.

Giant Plasma Waves May Be Stripping Away Mars’ Atmosphere

Kelvin–Helmholtz waves may help the solar wind strip atmospheric particles from Mars.

Mars is continually exposed to a stream of charged particles racing outward from the Sun. Earth’s global magnetic field deflects much of this solar wind, but Mars lacks a comparable shield. The flow can therefore strike the planet’s upper atmosphere directly and gradually carry some of its particles into space.

Researchers led by Boston University have identified one way this atmospheric loss may occur. Their study, published in Science Advances, found that the solar wind can disturb the outer edge of the Martian atmosphere much as wind agitates the surface of water. The interaction produces large rolling structures called Kelvin–Helmholtz waves, which can help pull atmospheric material away from the planet.

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