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Category: particle physics – Page 44

Galaxies are not islands in the cosmos. While globally the universe expands—driven by the mysterious “dark energy”—locally, galaxies cluster through gravitational interactions, forming the cosmic web held together by dark matter’s gravity. For cosmologists, galaxies are test particles to study gravity, dark matter and dark energy.

For the first time, MPA researchers and alumni have now used a novel method that fully exploits all information in galaxy maps and applied it to simulated but realistic datasets. Their study demonstrates that this new method will provide a much more stringent test of the cosmological standard model, and has the potential to shed new light on gravity and the dark universe.

From tiny fluctuations in the primordial universe, the vast cosmic web emerged: galaxies and form at the peaks of (over)dense regions, connected by cosmic filaments with empty voids in between. Today, millions of galaxies sit across the cosmic web. Large galaxy surveys map those galaxies to trace the underlying spatial matter distribution and track their growth or temporal evolution.

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The team found that the sharing of information that defines entanglement occurs across whole groups of fundamental particles called quarks and gluons within a proton.

“Before we did this work, no one had looked at entanglement inside of a proton in experimental high-energy collision data,” team member and Brookhaven Lab physicist Zhoudunming Tu said in a statement. “For decades, we’ve had a traditional view of the proton as a collection of quarks and gluons, and we’ve been focused on understanding so-called single-particle properties, including how quarks and gluons are distributed inside the proton.

Now, with evidence that quarks and gluons are entangled, this picture has changed. We have a much more complicated, dynamic system.

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Quantum physics is a very diverse field: it describes particle collisions shortly after the Big Bang as well as electrons in solid materials or atoms far out in space. But not all quantum objects are equally easy to study. For some—such as the early universe—direct experiments are not possible at all.

However, in many cases, quantum simulators can be used instead: one quantum system (for example, a cloud of ultracold atoms) is studied in order to learn something about another system that looks physically very different, but still follows the same laws, i.e. adheres to the same mathematical equations.

It is often difficult to find out which equations determine a particular quantum system. Normally, one first has to make theoretical assumptions and then conduct experiments to check whether these assumptions prove correct.

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Nuclear fission is the most reliable source of antineutrinos, but they are difficult to characterize. A recent study suggests how their emission can be simulated most effectively.

Antineutrinos are mysterious fundamental anti-particles with no charge and an exceptionally small but non-zero mass. The JUNO project (Jiangmen Underground Neutrino Observatory) in China is a large scintillation detector designed to detect them and to characterize their properties, particularly in precise measurements of that tiny mass. Anti-particles are hard to measure and even harder to control, even when they come from a strong and reliable source.

A group of Italian physicists, led by Monica Sisti of the Istituto Nazionale di Fisica Nucleare (INFN) in Milan and Antonio Cammi of the Politecnico di Milano and part of the JUNO collaboration of over 700 scientists from 17 countries, has now modeled parameters that determine the ‘antineutrino spectrum’ emitted by a source.

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Phase transitions in the collective motions of self-propelled particles are directly impacted both by the initial velocity of each particle, and the repulsive radius surrounding them.

Collective motions of self-propelled particles can be found across many systems in nature. One of the most striking features of this phenomenon is the way in which systems transition between different states of motion: a behavior which can be compared directly with in physics. So far, however, it is still not fully understood how these transitions are impacted by the initial parameters of these deeply .

Through analysis published in The European Physical Journal E, Salma Moushi and colleagues at the University of Hassam II, Morocco, show how the conditions required for transitions to occur are heavily dependent on the initial velocities of each particle, and the repulsion radius surrounding them.

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USTC researchers created a groundbreaking on-chip photonic simulator, leveraging thin-film lithium niobate chips to simplify quantum simulations of complex structures, achieving high-dimensional synthetic dimensions with reduced frequency demands.

A research team led by Prof. Chuanfeng Li from the University of Science and Technology of China (USTC) has made a significant breakthrough in quantum photonics. The team successfully developed an on-chip photonic simulator capable of modeling arbitrary-range coupled frequency lattices with gauge potential. This achievement was detailed in a recent publication in Physical Review Letters.

<em>Physical Review Letters (PRL)</em> is a prestigious peer-reviewed scientific journal published by the American Physical Society. Launched in 1958, it is renowned for its swift publication of short reports on significant fundamental research in all fields of physics. PRL serves as a venue for researchers to quickly share groundbreaking and innovative findings that can potentially shift or enhance understanding in areas such as particle physics, quantum mechanics, relativity, and condensed matter physics. The journal is highly regarded in the scientific community for its rigorous peer review process and its focus on high-impact papers that often provide foundational insights within the field of physics.

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A groundbreaking study has revealed a new regime of cooperative radiative phenomena, addressing a 70-year-old puzzle in quantum optics.

By using arrays of synthetic atoms and ultracold matter waves, they uncovered previously unseen collective spontaneous emission effects. These findings not only advance our understanding of fundamental quantum behaviors but also hold promise for practical applications, such as enhancing long-distance quantum networks and improving technologies in quantum science.

Quantum Optical Phenomena

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For the first time, scientists have observed a collection of particles, also known as a quasiparticle, that’s massless when moving one direction but has mass in the other direction. The quasiparticle, called a semi-Dirac fermion, was first theorized 16 years ago, but was only recently spotted inside a crystal of semi-metal material called ZrSiS. The observation of the quasiparticle opens the door to future advances in a range of emerging technologies from batteries to sensors, according to the researchers.

The team, led by scientists at Penn State and Columbia University, recently published their discovery in the journal Physical Review X.

“This was totally unexpected,” said Yinming Shao, assistant professor of physics at Penn State and lead author on the paper. “We weren’t even looking for a semi-Dirac fermion when we started working with this material, but we were seeing signatures we didn’t understand—and it turns out we had made the first observation of these wild quasiparticles that sometimes move like they have mass and sometimes move like they have none.”

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Did you see the Northern Lights this week? The new year arrived not only with fireworks, but with displays of aurora across the world at much more southerly latitudes than is normal.

Aurora were spotted as far south as Mexico, Colorado, Arizona, Wales in the U.K and France, with spectacular displays in Alaska, Scandinavia and New Zealand, according to SpaceWeather.com.

The display aurora came in the wake of forecasts for northern and Midwest U.S. states after a flurry of solar flares from the sun’s surface in the last few days of 2024, most notably an X-class event on Dec. 29 that hurled two clouds of charged particles in Earth’s direction.

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Scientists are exploring 2D materials — sheets just one atom thick — with unique and promising electronic properties.

When two of these sheets are layered at specific angles, they can exhibit remarkable behaviors, such as superconductivity. Antonija Grubišić-Čabo, a materials scientist at the University of Groningen, and her colleagues investigated one such “twisted” material and found that it behaved in ways that defied existing theoretical predictions.

2D Materials and Superconductivity.

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