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Category: particle physics

Water’s enigmatic surface: X-ray snapshots reveal atoms and molecules at work

Water is all around us, yet its surface layer—home to chemical reactions that shape life on Earth—is surprisingly hard to study. Experiments at SLAC’s X-ray laser are bringing it into focus.

Two-thirds of Earth’s surface is covered in water, most of it in oceans so deep and vast that only one-fifth of their total volume has been explored. Surprisingly, though, the most accessible part of this watery realm—the water’s surface, exposed on wave tops, raindrops and ponds full of skittering water striders—is one of the hardest to get to know.

Just a few layers of atoms thick, the surface plays an outsized role in the chemistry that makes our world what it is—from the formation of clouds and the recycling of water through rainfall to the ocean’s absorption of carbon dioxide from the atmosphere.

NASA Balloon Detects Strange Signals Coming From Ice in Antarctica

Unusual radio signals from beneath Antarctica’s ice continue to defy explanation. Several years ago, scientists using a cosmic particle detector in Antarctica recorded a series of puzzling radio signals, according to an international research collaboration that includes experts from Penn State. Bet

Tetraquark measurements could shed more light on the strong nuclear force

Identifying and studying tetraquarks and pentaquarks helps physicists to better understand how the strong force binds quarks together. This force also binds protons and neutrons in atomic nuclei.

Physicists are still divided as to the nature of these exotic hadrons. Some models suggest that their quarks are tightly bound via the strong force, so making these hadrons compact objects. Others say that the quarks are only loosely bound. To confuse things further, there is evidence that in some exotic hadrons, the quarks might be both tightly and loosely bound at the same time.

Now, new findings from the CMS Collaboration suggest that tetraquarks are tightly bound, but they do not completely rule out other models.

Elusive Quantum Interactions Tracked During Cooling

Over the past few decades, researchers have used ultracold atomic gases to simulate high-temperature superconductors and other materials in which electrons interact strongly. Frustratingly, these experiments have failed to uncover the temperature dependence of certain “p-wave” interactions relevant to some superconductors and superfluids. Now Kenta Nagase and his colleagues at the Institute of Science Tokyo have tracked how these interactions change as a cloud of lithium atoms is cooled toward absolute zero [1]. The results could help scientists better understand the behavior of certain exotic superconductors.

In a p-wave interaction, particles collide with each other in such a way that their interaction strength depends on their relative orientations. The inherent complexity of these interactions, such as their occurrence through three different scattering channels, meant that their predicted temperature dependence lacked experimental confirmation. To surmount this hurdle, Nagase and his colleagues isolated and analyzed the contributions to the interactions from each channel. They repeated their experiment at many temperatures, controlled by the strength of the optical trap confining the lithium cloud.

As they cooled the lithium cloud, Nagase and his colleagues saw that the strength of p-wave interactions increased, in agreement with predictions. These interactions caused the lithium atoms to briefly form fragile molecules, mimicking the pairing of electrons in a superconductor. The measured number, angular distribution, and behavior of such molecules were also consistent with expectations. These properties had been explored in the lab only partially, so the new work provides stronger support for current models of ultracold atomic gases.

Laser pulse ‘sculpting’ unlocks new control over particle acceleration

In high-intensity laser–matter interactions, including laser-induced particle acceleration, physicists generally want to work with the highest possible focused laser peak power, which is the ratio of energy per unit area to pulse duration. Therefore, for the same pulse energy and focus, the highest peak intensity can be achieved with the shortest pulse duration.

According to Károly Osvay, head of the National Laser-Initiated Transmutation Laboratory (SZTE NLTL) at the University of Szeged, it has long been known that by changing the so-called spectral phase in a laser pulse, it is possible to ensure that the components of the pulse reach the target in a specific temporal sequence. This ultimately allows the temporal shape of the pulse to be influenced.

“We looked at what happens when we change the relative timing of the frequency components. We confirmed that the order of the components influences which particles we can accelerate best and to what extent. In the case of deuterated solid-state foils, for example, we can change the ratio of accelerated proton and deuteron ions, as well as the ratio of the forward and backward accelerated species. All this is fundamentally influenced by the complex temporal shape of the laser pulse,” said the researcher.

Physicists made atoms behave like a quantum circuit

Using ultracold atoms and laser light, researchers recreated the behavior of a Josephson junction—an essential component of quantum computers and voltage standards. The appearance of Shapiro steps in this atomic system reveals a deep universality in quantum physics and makes elusive microscopic effects visible for the first time.

Josephson junctions play a central role in modern physics and technology. They enable extremely precise measurements, define the international standard for electrical voltage, and serve as essential components inside many quantum computers. Despite their importance, the quantum-scale processes occurring inside superconductors are notoriously difficult to observe directly.

To overcome this challenge, researchers at the RPTU University of Kaiserslautern-Landau turned to quantum simulation. Instead of studying electrons inside a solid material, they recreated the Josephson effect using ultracold atoms. Their approach involved separating two Bose-Einstein condensates (BECs) with an exceptionally thin optical barrier created by a focused laser beam that was moved in a controlled, periodic way. Even in this atomic system, the defining signatures of Josephson junctions emerged. The experiment revealed Shapiro steps, which are distinct voltage plateaus that appear at multiples of a driving frequency, just as they do in superconducting devices. Published in the journal Science, the work stands as a clear example of how quantum simulation can uncover hidden physics.

Entanglement enhances the speed of quantum simulations, transforming long-standing obstacles into a powerful advantage

Researchers from the Faculty of Engineering at The University of Hong Kong (HKU) have made a significant discovery regarding quantum entanglement. This phenomenon, which has long been viewed as a significant obstacle in classical quantum simulations, actually enhances the speed of quantum simulations. The findings are published in Nature Physics in an article titled “Entanglement accelerates quantum simulation.”

Simulating the dynamic evolution of matter is fundamental to understanding the universe, yet it remains one of the most challenging tasks in physics and chemistry. For decades, “entanglement”—the complex correlation between quantum particles—has been viewed as a formidable barrier. In classical computing, high entanglement makes simulations exponentially harder to perform, often acting as a bottleneck for studying complex quantum systems.

Led by Professor Qi Zhao from the School of Computing and Data Science at HKU, the research team collaborated with Professor You Zhou from Fudan University and Professor Andrew M. Childs from the University of Maryland, and overturned this long-held belief. They discovered that while entanglement hinders classical computers, it actually accelerates quantum simulations, turning a former obstacle into a powerful resource.

Unexpected oscillation states in magnetic vortices could enable coupling across different physical systems

Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) have uncovered previously unobserved oscillation states—so-called Floquet states—in tiny magnetic vortices. Unlike earlier experiments, which required energy-intensive laser pulses to create such states, the team in Dresden discovered that a subtle excitation with magnetic waves is sufficient.

This finding not only raises fundamental questions in basic physics but could also eventually serve as a universal adapter bridging electronics, spintronics, and quantum devices. The team reports the results in the journal Science.

Magnetic vortices can form in ultrathin, micron-sized disks of magnetic materials such as nickel–iron. Within these vortices, the elementary magnetic moments—tiny compass needles—arrange themselves in circular patterns.

Behind nature’s blueprints: Physicists create ‘theoretical rulebook’ of self-assembly

Inspired by biological systems, materials scientists have long sought to harness self-assembly to build nanomaterials. The challenge: the process seemed random and notoriously difficult to predict.

Now, researchers from the Institute of Science and Technology Austria (ISTA) and Brandeis University have uncovered geometric rules that act as a master control panel for self-assembling particles.

The results, which could find applications ranging from protein design to synthetic nanomachines, were published in Nature Physics.

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