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Category: particle physics

A magnetically levitated particle enables researchers to search for ultralight dark matter

Dark matter, although not visible, is believed to make up most of the total mass of the universe. One theory suggests that ultralight dark matter behaves like a continuous wave, which could exert rhythmic forces that are detectable only with ultra-sensitive quantum instrumentation.

New research published in Physical Review Letters and led by Rice University physicist Christopher Tunnell and postdoctoral researcher Dorian Amaral, the study’s first author and lead analyst, sees the first direct search for ultralight using a magnetically levitated particle.

In collaboration with physicists from Leiden University, the team suspended a microscopic neodymium magnet inside a superconducting enclosure cooled to near absolute zero. The setup was designed to detect subtle oscillations believed to be caused by dark matter waves moving through Earth.

A new approach to probing Landauer’s principle in the quantum many-body regime

Landauer’s principle is a thermodynamics concept also relevant in information theory, which states that erasing one bit of information from an information system results in the dissipation of at least a specific amount (i.e., kBTln2) of energy. This principle has so far been primarily considered in the context of classical computers and information processing systems.

Yet researchers at TU Vienna, the Freie Universität Berlin, the University of British Columbia, the University of Crete and the Università di Pavia recently extended Landauer’s principle to quantum many-body systems, systems made up of many interacting .

Their paper, published in Nature Physics, introduces a viable approach to experimentally probe this crucial principle in a quantum regime and test rooted in quantum thermodynamics.

Tiny collider experiment determines three electrons are enough for strong interactions between particles

Three electrons are enough to trigger strong interactions between particles. That is what was demonstrated by scientists from the CNRS and l’Université de Grenoble Alpes, in collaboration with teams from Germany and Latvia, in a study published in the journal Nature.

With the help of a tiny collider they built themselves, the researchers successfully “accelerated” up to five at the same time toward a separation barrier, and counted the number of electrons present on each side.

The result: Three electrons are enough to show between particles. With five electrons, the interactions become so intense that they imitate the behavior of hundreds of billions of electrons. Placed together, these three particles form an actual “heap” in the .

It’s elementary: Problem-solving AI approach tackles inverse problems used in nuclear physics and beyond

Solving life’s great mysteries often requires detective work, using observed outcomes to determine their cause. For instance, nuclear physicists at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility analyze the aftermath of particle interactions to understand the structure of the atomic nucleus.

This type of subatomic sleuthing is known as the inverse problem. It is the opposite of a forward problem, where causes are used to calculate the effects. Inverse problems arise in many descriptions of physical phenomena, and often their solution is limited by the experimental data available.

That’s why scientists at Jefferson Lab and DOE’s Argonne National Laboratory, as part of the QuantOm Collaboration, have led the development of an artificial intelligence (AI) technique that can reliably solve these types of puzzles on supercomputers at large scales.

Orbiter pair expands view of Martian ionosphere

Like Earth, Mars is surrounded by an ionosphere—the part of its upper atmosphere where radiation from the sun knocks electrons off of atoms and molecules, creating charged particles. The Martian ionosphere is complex and continuously changes over the course of the day, but its role in atmospheric dynamics and radio communication signals means understanding it is key for Mars exploration.

One way to study the Martian is with radio occultation, in which a spacecraft orbiting Mars sends a to a receiver on Earth. When it skims across the Martian ionosphere, the signal bends slightly. Researchers can measure this refraction to learn about Martian ionospheric properties such as electron density and temperature. However, the relative positions of Mars, Earth, and the sun mean conventional radio occultation cannot measure the middle of the Martian day.

Now, in an article published in the Journal of Geophysical Research: Planets, Jacob Parrot and colleagues deepen our understanding of the Martian ionosphere using an approach called mutual radio occultation, in which the radio signal is sent not from an orbiter to Earth but between two Mars orbiters. As one orbiter rises or sets behind Mars from the other’s perspective, the signal passes through the ionosphere and refracts according to the ionosphere’s properties.

Breakthrough theory links Einstein’s relativity and quantum mechanics

For over 100 years, two theories have shaped our understanding of the universe: quantum mechanics and Einstein’s general relativity. One explains the tiny world of particles; the other describes gravity and the fabric of space. But despite their individual success, bringing them together has remained one of science’s greatest unsolved problems.

Now, a team of researchers at University College London has introduced a bold new idea. Rather than tweaking Einstein’s theory to fit into quantum rules, they suggest flipping the script. Their model, called a “postquantum theory of classical gravity,” aims to rethink the deep link between gravity and the quantum world.

Quantum mechanics thrives on probabilities, uncertainty, and the strange behavior of subatomic particles. It’s helped explain the structure of atoms and power modern technology. Meanwhile, general relativity offers a grand view of the universe, where planets and stars bend spacetime and create what we feel as gravity.

New Approach to Controlling Light Signals

A concept based on an exotic effect in periodic structures may be useful for developing future photonic devices.

A new way to marshal light within optical devices has been demonstrated experimentally by researchers in China. They have been able to induce light to organize itself into specific patterns of pulses as it circulates within a pair of optical fiber loops using a version of a phenomenon—called the non-Hermitian skin effect (NHSE)—that has been predicted but not observed previously [1]. The effect could be used to control light signals in photonic devices such as switches and routers.

In the standard theory for electron behavior in a metallic crystal, the periodic atomic structure leads to so-called Bloch waves—electron quantum states that spread across the entire crystal. But in recent years, theorists have found surprising results for a scenario in which one assumes that a particle such as an electron hops between neighboring sites in a periodic lattice asymmetrically—say, rightward hopping is more probable than leftward hopping. The particle’s quantum states become localized at the edge or surface of the lattice rather than spreading across it. This localization is the NHSE.

Quantum spin currents in graphene without external magnetic fields pave way for ultra-thin spintronics

Scientists from TU Delft (The Netherlands) have observed quantum spin currents in graphene for the first time without using magnetic fields. These currents are vital for spintronics, a faster and more energy-efficient alternative to electronics. This breakthrough, published in Nature Communications, marks an important step towards technologies like quantum computing and advanced memory devices.

Quantum physicist Talieh Ghiasi has demonstrated the quantum Hall (QSH) effect in graphene for the first time without any external magnetic fields. The QSH effect causes electrons to move along the edges of the graphene without any disruption, with all their spins pointing in the same direction.

“Spin is a quantum mechanical property of electrons, which is like a tiny magnet carried by the electrons, pointing up or down,” Ghiasi explains. “We can leverage the spin of electrons to transfer and process information in so-called spintronics devices. Such circuits hold promise for next-generation technologies, including faster and more energy-efficient electronics, quantum computing, and advanced memory devices.”

Researchers confirm fundamental conservation laws at the quantum level

Researchers at Tampere University and their collaborators from Germany and India have experimentally confirmed that angular momentum is conserved when a single photon is converted into a pair – validating a key principle of physics at the quantum level for the first time. This breakthrough opens new possibilities for creating complex quantum states useful in computing, communication, and sensing.

Conservation laws are the heart of our natural scientific understanding as they govern which processes are allowed or forbidden. A simple example is that of colliding billiard balls, where the motion – and with it, their linear momentum – is transferred from one ball to another. A similar conservation rule also exists for rotating objects, which have angular momentum. Interestingly, light can also have an angular momentum, e.g., orbital angular momentum (OAM), which is connected to the light’s spatial structure.

In the quantum realm, this implies that single particles of light, so-called photons, have well-defined quanta of OAM, which need to be conserved in light-matter interactions. In a recent study in Physical Review Letters, researchers from Tampere University and their collaborators, have now pushed the test of these conservation laws to absolute quantum limit. They explore if the conservation of OAM quanta holds when a single photon is split into a photon pair.