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Category: particle physics – Page 13

For over a century, physicists have grappled with one of the most profound questions in science: How do the rules of quantum mechanics, which govern the smallest particles, fit with the laws of general relativity, which describe the universe on the largest scales?

The optical lattice clock, one of the most precise timekeeping devices, is becoming a powerful tool used to tackle this great challenge. Within an optical lattice clock, atoms are trapped in a “lattice” potential formed by laser beams and are manipulated with precise control of quantum coherence and interactions governed by .

Simultaneously, according to Einstein’s laws of general relativity, time moves slower in stronger gravitational fields. This effect, known as gravitational redshift, leads to a tiny shift of atoms’ internal energy levels depending on their position in gravitational fields, causing their “ticking”—the oscillations that define time in optical lattice clocks—to change.

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Many physicists and engineers have recently been trying to demonstrate the potential of quantum computers for tackling some problems that are particularly demanding and are difficult to solve for classical computers. A task that has been found to be challenging for both quantum and classical computers is finding the ground state (i.e., lowest possible energy state) of systems with multiple interacting quantum particles, called quantum many-body systems.

When one of these systems is placed in a thermal bath (i.e., an environment with a fixed temperature that interacts with the systems), it is known to cool down without always reaching its . In some instances, a can get trapped at a so-called local minimum; a state in which its energy is lower than other neighboring states but not at the lowest possible level.

Researchers at California Institute of Technology and the AWS Center for Quantum Computing recently showed that while finding the local minimum for a system is difficult for classical computers, it could be far easier for quantum computers.

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A collaborative research team has introduced a nitrogen-centric framework that explains the light-absorbing effects of atmospheric organic aerosols. Published in Science, this study reveals that nitrogen-containing compounds play a dominant role in the absorption of sunlight by atmospheric organic aerosols worldwide. This discovery signifies a major step towards improving climate models and developing more targeted strategies to mitigate the climate impact of airborne particles.

Atmospheric organic aerosols influence climate by absorbing and scattering sunlight, particularly within the near-ultraviolet to visible range. Due to their complex composition and continuous chemical transformation in the atmosphere, accurately assessing their climate effects has remained a challenge.

The study was jointly led by Prof. Fu Tzung-May, Professor of the School of Environmental Science and Engineering at Southern University of Science and Technology (SUSTech) and National Center for Applied Mathematics Shenzhen (NCAMS), and Prof. Yu Jianzhen, Chair Professor of the Department of Chemistry and the Division of Environment and Sustainability at Hong Kong University of Science and Technology (HKUST).

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Scientists at Yokohama National University, in collaboration with RIKEN and other institutions in Japan and Korea, have made an important discovery about how electrons move and behave in molecules. This discovery could potentially lead to advances in electronics, energy transfer, and chemical reactions.

Published in the Science, their study reveals a new way to control the distribution of electrons in molecules using very fast phase-controlled pulses of light in the .

Atoms and molecules contain negatively charged electrons that usually stay in specific energy levels, like layers, around the positively charged nucleus. The way these electrons are arranged in the molecule is key to how the molecule behaves.

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A small international team of nanotechnologists, engineers and physicists has developed a way to force laser light into becoming a supersolid. Their paper is published in the journal Nature. The editors at Nature have published a Research Briefing in the same issue summarizing the work.

Supersolids are entities that exist only in the quantum world, and, up until now, they have all been made using . Prior research has shown that they have zero viscosity and are formed in crystal-like structures similar to the way atoms are arranged in salt crystals.

Because of their nature, supersolids have been created in extremely cold environments where the can be seen. Notably, one of the team members on this new effort was part of the team that demonstrated more than a decade ago that light could become a fluid under the right set of circumstances.

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Neutrinos generated through solar fusion reactions travel effortlessly through the sun’s dense core. Each specific fusion process creates neutrinos with distinctive signatures, potentially providing a method to examine the sun’s internal structure. Multiple neutrino detection observatories on Earth are now capturing these solar particles, which can be analyzed alongside reactor-produced neutrinos with the data eventually enabling researchers to construct a detailed map of the interior of the sun.

The sun is a massive sphere of hot plasma at the center of our solar system and provides the light and heat to make life on Earth possible. Composed mostly of hydrogen and helium, it generates energy through , converting hydrogen into helium in its core. This process releases an enormous amount of energy which we perceive as heat and light.

The sun’s surface, or photosphere, is around 5,500°C, while its core reaches over 15 million°C. It influences everything from our climate to space weather, sending out and occasional bursts of radiation known as . As an average middle-aged star, the sun is about 4.6 billion years old and will (hopefully) continue burning for another 5 billion years before evolving into a red giant and eventually becoming a white dwarf.

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Periodic structures known as metamaterials can interact with electromagnetic waves in unusual ways. In one counterintuitive example, standing waves remain trapped in a volume even though they’re surrounded by radiating waves that should carry their energy away. These standing waves, called bound states in the continuum (BICs), can provide a boost to resonant systems—such as lasers, filters, or sensors—by mitigating radiative losses. Researchers have recently demonstrated a promising design that produces high-quality BICs; however, it works only at microwave frequencies. Simulations by Pietro Brugnolo and his colleagues at the Technical University of Denmark now suggest that a straightforward change could allow the design to be adapted to optical wavelengths [1].

The previous design involves thin metamaterials, or metasurfaces, made of metallic bars arranged around cylindrical cavities. In such a configuration, BICs emerge when characteristic metasurface resonances match the cavity resonance. The metallic elements, however, result in resistive losses when used at wavelengths shorter than those of microwaves. Brugnolo’s team thus set out to investigate an all-dielectric version of the scheme.

The researchers simulated devices in which the metallic elements were replaced with silicon particles distributed on a cylindric surface. Their results showed that the structure displayed both an electrical and an effective magnetic response, which could be tailored to create the standing-wave patterns characteristic of BICs. For a wave at telecommunication wavelengths (1550 nm), their simulations predicted a cavity quality factor of 1.7 × 104, on par with the microwave version of the same scheme.

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A fundamental goal of physics is to explain the broadest range of phenomena with the fewest underlying principles. Remarkably, seemingly disparate problems often exhibit identical mathematical descriptions.

For instance, the rate of heat flow can be modeled using an equation very similar to that governing the speed of particle diffusion. Another example involves wave equations, which apply to the behavior of both water and sound. Scientists continuously seek such connections, which are rooted in the principle of the “universality” of underlying physical mechanisms.

In a study published in the journal Royal Society Open Science, researchers from Osaka University uncovered an unexpected connection between the equations for defects in a and a well-known formula from electromagnetism.

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UC Santa Barbara researchers are working to move cold atom quantum experiments and applications from the laboratory tabletop to chip-based systems, opening new possibilities for sensing, precision timekeeping, quantum computing and fundamental science measurements.

“We’re at the tipping point,” said electrical and computer engineering professor Daniel Blumenthal.

In an invited article that was also selected for the cover of Optica Quantum, Blumenthal, along with graduate student researcher Andrei Isichenko and postdoctoral researcher Nitesh Chauhan, lays out the latest developments and future directions for trapping and cooling the atoms that are fundamental to these experiments—and that will bring them to devices that fit in the palm of your hand.

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Researchers discovered how Floquet Majorana fermions can improve quantum computing by controlling superconducting currents, potentially reducing errors and increasing stability. A new study has revealed significant insights into the behavior of electric current flow in superconductors, which could contribute to advancements in controlled quantum information processing.

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