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Category: particle physics

Why the intrinsic quantum effects of axion dark matter are completely undetectable

Dark matter is an elusive form of matter that almost never emits, absorbs or reflects light, while only weakly interacting with regular matter. These properties make it very difficult to detect using conventional experimental techniques and instruments.

Over the past decades, physicists have inferred the existence of dark matter indirectly, by probing its influence on the gravity of stars, galaxies and other cosmological objects. As it has never been directly observed before, the exact composition and nature of dark matter remain unknown.

A hypothetical dark matter particle is the axion, an ultralight particle that is predicted to be highly abundant in the universe. Most existing work describes axions as a classical field, a wave-like entity that resembles an electromagnetic field.

Nickelate reveals nodeless gap, providing key clue to high-temperature superconductivity

The mechanism of high-temperature (TC) superconductivity is a key challenge in condensed matter physics. Recently, Chinese scientists made significant progress in the study of high-TC nickelate superconductors.

For the first time, scientists observed a nodeless superconducting gap and discovered electron-boson coupling by measuring the electronic structures of Ruddlesden-Popper bilayer nickelate superconducting thin films. These results provide crucial evidence for two fundamental issues in the mechanism of high-TC nickelates: “superconducting gap symmetry” and “superconducting pairing mechanism.”

This study, conducted by a team led by Prof. He Junfeng from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences, in collaboration with a team led by Prof. Xue Qikun and Prof. Chen Zhuoyu from the Southern University of Science and Technology (SUSTech), was published in Science.

Scientists just captured a mysterious quantum “dance” inside superconductors

Scientists just spotted a mysterious quantum “dance” that could rewrite superconductivity—and reshape future tech. For the first time, researchers have directly visualized the quantum behavior that drives superconductivity, a state in which paired electrons allow electricity to flow with zero resistance at very low temperatures.

But what they observed came as a surprise.

In a study published April 15 in Physical Review Letters, the team captured images of individual atoms forming pairs inside a specially prepared gas cooled to nearly absolute zero — the unreachable limit to how cold anything can get. This system, known as a Fermi gas, lets scientists replace electrons with atoms so they can study superconductivity in a highly controlled environment.

Unusual nonlinear thermoelectric effect appears in chiral tellurium, confirming theoretical predictions

An unusual thermoelectric effect has been observed in the semiconductor tellurium by RIKEN physicists for the first time. This demonstration points to the potential of similar materials to be used in applications such as energy harvesting and advanced heat management.

Thermoelectric materials can convert electricity into heat and vice versa. For most of them, doubling the voltage across them will double the heat they produce. But for some special thermoelectric materials, there is a nonlinear relationship between voltage and heat. Such nonlinear thermoelectric materials are useful for applications that require heat to flow in one direction and for generating electricity from thermal fluctuations.

Some theoretical calculations have predicted that even more exotic nonlinear thermoelectric effects will occur in materials where the atoms or molecules have a chiral arrangement. But they hadn’t been observed in the lab—until now.

Crystals of space and time: A structural phenomenon that may collapse into tiny black holes

A team from Vienna and Frankfurt has found a formula describing a strange phenomenon: Space and time can form a kind of “crystal” that may turn into a black hole. The results are described in Physical Review Letters.

Alongside the famous gigantic black holes, physics also allows for microscopic versions. They emerge from so-called critical states, when spacetime organizes itself into a regular, crystal-like structure during a process known as critical collapse. A team from Goethe University Frankfurt and TU Wien has now succeeded, for the first time, in describing this phenomenon with an exact mathematical formula using an unusual mathematical trick.

Black holes usually form in spectacular events, such as the death of a massive star. But in theory, arbitrarily small black holes are also possible: tiny microscopic objects that can emerge from special critical states after the slightest addition of energy. Such states may have existed shortly after the Big Bang, when the universe was still a chaotic mixture of particles, potentially giving rise to so-called primordial black holes.

What if the direction of a magnet could shape the building blocks of life?

In a new discovery, researchers from the Hebrew University of Jerusalem and the Weizmann Institute of Science have found that something in the direction of a magnetic field can influence how molecules of life behave at the most fundamental level and how early chemical processes linked to life may have unfolded.

The study, published in Chem and led by Prof. Yossi Paltiel (Hebrew University) and Prof. Michal Sharon (Weizmann Institute), shows that tiny differences between atoms (different isotopes) can lead to measurable changes in molecular behavior when combined with an invisible quantum property known as electron spin. Separation of the different isotopes can be achieved by magnetic surfaces.

At the center of the story is L-methionine, an amino acid, a basic building block of life. Like other biological molecules, methionine has a specific “handedness,” meaning it exists in a form that is not identical to its mirror image. This property, called chirality, is a mystery: why did nature choose one “hand” over the other?

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