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Category: particle physics – Page 3

Physicists bring unruly molecules to the quantum party

Scientists have made leaps and bounds in bending atoms to their will, making them into everything from ultraprecise clocks to bits of quantum data. Translating these quantum technologies from obedient atoms to unruly molecules could offer greater possibilities. Molecules can rotate and vibrate. That makes molecules more sensitive to certain changes in the environment, like temperature.

“If you’re sensitive to something, it can be a curse, because you would like to not be sensitive, or it can be a blessing,” said NIST physicist Dietrich Leibfried. “You can use that sensitivity to your advantage.”

But that same sensitivity has made molecules difficult to control. Recently, physicists at the National Institute of Standards and Technology (NIST) achieved new levels of control over molecules. In a study published in Physical Review Letters, they were able to manipulate a calcium hydride molecular ion—made up of one atom of hydrogen and one atom of calcium, with one electron removed to make it a charged molecule—with almost perfect success. And this control opens possibilities for quantum technology, chemical research and exploring new physics.

A simple spin swap reveals exotic anyons

Researchers from the University of Innsbruck, the Collège de France, and the Université Libre de Bruxelles have developed a simple yet powerful method to reveal anyons—exotic quantum particles that are neither bosons nor fermions—in one-dimensional systems. Their paper is published in Physical Review Letters.

In conventional three-dimensional space, particles belong to one of two categories: fermions or bosons. In low-dimensional settings, however, quantum mechanics allows for more exotic behavior. Here, anyons can emerge—quasi-particles whose exchange properties continuously interpolate between those of bosons and fermions, leading to fractional statistics. Detecting and engineering such particles in one dimension has long been a central challenge, typically requiring, as theory proposals suggest, intricate scattering schemes or density-dependent tunneling processes.

The new study by teams led by Hanns-Christoph Nägerl at the University of Innsbruck and Nathan Goldman at the Université Libre de Bruxelles and Collège de France (CNRS) now introduces a remarkably simple yet powerful approach. The researchers propose an effective “swap” model that leverages the spin degree of freedom of ultracold atoms. By assigning a complex phase to the exchange—or “swap”—of two spins, the system naturally acquires the fractional statistical behavior characteristic of anyons.

Bazinga! Physicists crack a ‘Big Bang Theory’ problem that could help explain dark matter

A professor at the University of Cincinnati and his colleagues have figured out something two of America’s most famous fictional physicists couldn’t: how to theoretically produce subatomic particles called axions in fusion reactors.

Particle physicists Sheldon Cooper and Leonard Hofstadter, roommates in the sitcom “The Big Bang Theory,” worked on the problem in three episodes of Season 5, but couldn’t crack it.

Now UC physics Professor Jure Zupan and his theoretical physicist co-authors at the Fermi National Laboratory, MIT and Technion–Israel Institute of Technology think they have one solution in a study published in the Journal of High Energy Physics.

Silicon atom processor links 11 qubits with more than 99% fidelity

In order to scale quantum computers, more qubits must be added and interconnected. However, prior attempts to do this have resulted in a loss of connection quality, or fidelity. But, a new study published in Nature details the design of a new kind of processor that overcomes this problem. The processor, developed by the company Silicon Quantum Computing, uses silicon—the main material used in classical computers—along with phosphorus atoms to link 11 qubits.

The new design uses precision-placed phosphorus atoms in isotopically purified silicon-28, which are arranged into two multi-nuclear spin registers. One register contains four phosphorus atoms, while the other contains five, and each register shares an electron spin. The two registers are linked by electron exchange interaction, allowing for non-local connectivity across the registers and 11 linked qubits.

Because of the placement of silicon and phosphorus in the periodic table, the design is referred to as the “14|15 platform.” This 11-qubit atom processor in silicon is the largest of its kind to date, marking a major accomplishment for quantum computing.

Scientists build a quantum computer that can repair itself using recycled atoms

Like their conventional counterparts, quantum computers can also break down. They can sometimes lose the atoms they manipulate to function, which can stop calculations dead in their tracks. But scientists at the US-based firm Atom Computing have demonstrated a solution that allows a quantum computer to repair itself while it’s still running.

The team zeroed in on quantum computers that use neutral atoms (atoms with equal numbers of protons and electrons). These individual atoms are the qubits, or the basic building blocks of a quantum computer’s memory. They are held in place by laser beams called optical tweezers, but the setup is not foolproof.

Occasionally, an atom slips out of its trap and disappears. When this happens mid-calculation, the whole process can grind to a halt because the computer can’t function with a missing part.

Flat Fermi surface in altermagnets enables quantum limit spin currents

The key feature of spintronic devices is their ability to use spin currents to transfer momentum, enabling low-energy, high-speed storage and logical signal control. These devices are usually manipulated by electric currents and fields. The charge-to-spin conversion efficiency (CSE) is a key metric for evaluating their performance.

Now, scientists from the Institute of Metal Research (IMR) of the Chinese Academy of Sciences have proposed a new deep correlation between the spin splitting torque (SST) and the Fermi surface geometry, achieving a quantum limit of 100% in a system with a flat Fermi surface. These results were published in Physical Review Letters on December 16.

Shortest light pulse ever created captures ultrafast electron dynamics

Electrons determine everything: how chemical reactions unfold, how materials conduct electricity, how biological molecules transfer energy, and how quantum technologies operate. But electron dynamics happens on attosecond timescales—far too fast for conventional measurement tools.

Researchers have now generated a 19.2-attosecond soft X-ray pulse, which effectively creates a camera capable of capturing these elusive dynamics in real time with unprecedented detail, enabling the observation of processes never observed before. Dr. Fernando Ardana-Lamas, Dr. Seth L. Cousin, Juliette Lignieres, and ICREA Prof. Jens Biegert, at ICFO, has published this new record in Ultrafast Science. At just 19.2 attoseconds long, it is the shortest and brightest soft X-ray pulse ever produced, giving rise to the fastest “camera” in existence.

Flashes of light in the soft X-ray spectral range provide fingerprinting identification, allowing scientists to track how electrons reorganize around specific atoms during reactions or phase transitions. Generating an isolated pulse this short, required innovations in high-harmonic generation, advanced laser engineering, and attosecond metrology. Together, these developments allow researchers to observe electron dynamics, which define material properties, at their natural timescales.

Color-superconducting quark matter may explain stability of massive neutron stars

Describing matter under extreme conditions, such as those found inside neutron stars, remains an unsolved problem. The density of such matter is equivalent to compressing around 100,000 Eiffel Towers into a single cubic centimeter. In particular, the properties of so-called quark matter—which consists of the universe’s fundamental building blocks, the quarks, and may exist in extremely dense regions—play a central role.

Researchers from TU Darmstadt and Goethe University Frankfurt have studied this matter and its thermodynamic properties. Their findings are published in the journal Physical Review Letters.

Theoretical studies suggest that quarks at very low temperatures enter a so-called color-superconducting state, which fundamentally alters the nature of matter. This state is analogous to the transition of an electron gas into an electrical superconductor—except that, instead of electrons, quarks pair up and create an energy gap in their excitation spectrum.

Electrochemical tuning of Ni-rich cathodes curbs c-collapse, enhancing lithium-ion battery durability

Lithium-ion batteries (LiBs) remain the most widely used rechargeable batteries worldwide, due to their light weight, high energy densities and their short charging times. Energy engineers have been trying to identify new materials and strategies that could help to further boost the energy stored by LiBs, while also extending their lifespan (i.e., the period for which they can be used reliably).

LiBs work by moving charged lithium atoms (i.e., ions) between a positive electrode (i.e., cathode) and a negative electrode (i.e., anode). When lithium ions enter and leave these materials, they can experience significant structural changes.

These changes include the sudden shrinkage of the spacing between the materials’ horizontal layers, which can be experimentally monitored through the crystal’s c-lattice parameter. This phenomenon, referred to as c-collapse, can deform the material, crack the particles and in turn shorten the life of batteries.

New Microscope Makes an Invisible 2D Material Visible

A new microscopy technique allows scientists to see single-atom-thick boron nitride by making it glow under infrared light. Researchers from the Physical Chemistry and Theory departments at the Fritz Haber Institute have developed a new way to visualize boron nitride layers that are just one atom

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