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Category: particle physics – Page 113

Measuring Particle Diffusion with the Countoscope

A new method for studying the behavior of multiparticle systems relies on a simple “head count” of particles in imaginary boxes.

One way to characterize the interactions in a bacterial colony or a polymer mixture is to trace the path of individual particles through the system, but such tracking can become difficult when the particles are indistinguishable. Researchers have developed a new method that extracts particle dynamics from a simple counting of particles in imaginary boxes of adjustable size [1]. They demonstrated this “countoscope” strategy in experiments with small plastic spheres moving around in a liquid. The measured rate of diffusion was different for different sized boxes, which revealed particle clumping. The countoscope’s ability to identify such collective behavior could one day help researchers understand the mechanisms that cause bacteria and other life forms to group together.

Biologists, chemists, and soft-matter physicists often study many-particle systems in which the particles shuffle around each other in a “random walk.” A useful measure of this behavior is the diffusion constant, which describes how fast an individual particle moves. A measurement of the diffusion constant can tell a biologist whether cells are healthy or sick, or it can tell a chemist how fast a molecule will move through a gel in a chemical-analysis device. The diffusion constant is typically determined by following the path of a single particle in a video recording. This trajectory reconstruction becomes difficult, however, when the particles are numerous and all look the same, says Sophie Marbach from Sorbonne University in France.

Discover the V-Score: The Secret Weapon in Quantum Problem Solving

Predicting the behavior of many interacting quantum particles is a complex task, but it’s essential for unlocking the potential of quantum computing in real-world applications. A team of researchers, led by EPFL, has developed a new method to compare quantum algorithms and identify the most challenging quantum problems to solve.

Quantum systems, from subatomic particles to complex molecules, hold the key to understanding the workings of the universe. However, modeling these systems quickly becomes overwhelming due to their immense complexity. It’s like trying to predict the behavior of a massive crowd where everyone constantly influences everyone else. When you replace the crowd with quantum particles, you encounter what’s known as the “quantum many-body problem.”

Quantum many-body problems involve predicting the behavior of numerous interacting quantum particles. Solving these problems could lead to major breakthroughs in fields like chemistry and materials science, and even accelerate the development of technologies like quantum computers.

Quarks, gluons can now be visible at low energies, reveal scientists

For many years, scientists believed that fundamental particles like protons and neutrons that form an atomic nucleus, can’t be divided further into smaller units. However, in the following years, physicists discovered quarks and gluons.

While quarks are particles that combine to form protons and neutrons, gluons act like glue, binding the quarks together.

So far, scientists have been studying the atomic nucleus using two models. In the first model, at low energies like in most typical nuclear experiments, they describe the atomic nucleus in terms of protons and neutrons. This is the classic way of understanding the nucleus.

A near-Earth microquasar emerges as a source of powerful radiation

Electromagnetic radiation of extremely high energies is produced not only in the jets launched from active nuclei of distant galaxies, but also in jet-launching objects lying within the Milky Way, called microquasars. This latest finding by scientists from the international High-Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) radically changes the previous understanding of the mechanisms responsible for the formation of ultra-high-energy and in practice marks a revolution in its further study.

Since the discovery of cosmic radiation by Victor Hess in 1912, astronomers have believed that the celestial bodies responsible in our galaxy for the acceleration of these particles up to the highest energies are the remains of gigantic supernova explosions, called supernova remnants.

However, a different picture comes from the latest data from the HAWC observatory: The sources of radiation of extremely high energies turn out to be microquasars. Astrophysicists from the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow played a key role in the discovery.

Researchers at MIT recently published the first results of an experiment aimed at searching for axion dark matter by probing the axion-induced birefringence of electromagnetic waves

While these findings, published in Physical Review Letters, did not lead to the observation of signals associated with these hypothetical dark matter particles, they established a new technique to search for axions using a tunable optical cavity.

New benchmark helps solve the hardest quantum problems

From subatomic particles to complex molecules, quantum systems hold the key to understanding how the universe works. But there’s a catch: when you try to model these systems, that complexity quickly spirals out of control—just imagine trying to predict the behavior of a massive crowd of people where everyone is constantly influencing everyone else. Turn those people into quantum particles, and you are now facing a “quantum many-body problem.”

Physicists report emergence of ferromagnetism at onset of Kondo breakdown in moiré bilayer lattices

In their previous research, Mak and his colleagues engineered a highly tunable moiré Kondo lattice system based on MoTe2/WSe2 moiré bilayers. This material offers a unique opportunity to examine the Kondo destruction transition in a continuous manner, which has proved highly challenging in bulk heavy fermion materials.

“With this background, our Nature Physics paper studied the fate of the heavy fermions by continuously tuning the density of the itinerant carriers in the system, which tunes the effective Kondo coupling strength,” said Mak. “Near a critical density, we observed a destruction of the heavy fermions and the simultaneous emergence of a ferromagnetic Anderson insulator.”

As part of their new study, the researchers examined the Kondo lattice physics emerging in the moiré semiconductor: angle-aligned MoTe2/WSe2 heterobilayer presented in their previous paper. Their results highlight the promise of moiré Kondo lattices for studying the Kondo destruction transition using a tunable platform, as well as the possibility of realizing other exotic states of matter near such transition.

A look into cloudy liquids: New method makes the expansion of turbid drops in water visible

When driving though a bank of fog, car headlights are only of limited help as the light is scattered by the water particles suspended in the air. The situation is similar when you try to observe the inside of a drop of milk in water or the internal structure of an opal gem with the help of white light. In all these cases, multiple light scattering effects prevent examination of the interior.