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Category: particle physics – Page 309

Information variations in a chain-like system are associated to energy transactions with the environment, which can take place reversibly or irreversibly, with a lower theoretical energy limit22,23. Fluctuations as a consequence of pure computations are on the order of the thermal level (i.e., similar to kT, being k the Boltzmann constant and T the absolute temperature), according to Landauer’s principle. Such energies are negligible at routine human scales but become significant when the size of the system is nanoscopic or smaller, because the work and heat it generates also compare with the thermal level. Small systems are based on nanostructures, including individual molecules and arrangements of atoms, such as biological and quantum systems.

Fluctuation theorems have appeared in recent years explaining quantitatively energy imbalances between forward and reverse pathways or between equilibrium and non-equilibrium processes24,25. They have been tested experimentally26,27,28, mostly in biomolecular systems analyzed on a one-by-one basis29. Most of these theorems establish relations among thermodynamic potentials for general systems, often with no specific insight into information theory. This theory, in turn, deals with spatially-indexed, 1-dimensional arrangements of symbols, which may not be necessarily associated to a time order. Recent generalizations separate the role of information and feedback control30,31, but still the interpretation of non-Markovianity, irreversibility and reversibility in terms of purely informational operations such as reading, writing and error correction32,33 remains obscured.

Here, we analyze energy exchanges associated to the symbolic management of a sequence of characters, without reference to the physical construction of the chain. Just by considering reversibility at the single sequence level and conservation laws, we next present two pairs of fluctuations equalities in the creation of information sequences, which use depends on energy exchange constraints. Our analysis integrates key information concepts, namely, reading, writing, proof reading and editing in the thermodynamic description of a string of symbols with information.

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Over the past decade, physicists have repeatedly scrutinized tanks containing tons of liquid xenon, hoping to spot the flashes of light that might indicate a collision between a dark matter particle and a xenon atom (see Viewpoint: Dark Matter Still at Large). Most of these studies were dedicated to detecting so-called weakly interacting massive particles (WIMPs), a leading dark matter candidate with a mass greater than 10 GeV. Now researchers have sifted through a new set of data for a much lighter prize: fermionic dark matter with a mass of a few tens of MeV [1]. Although the team found no signal beyond the expected background level, they have set the strongest constraints yet on models of sub-GeV fermionic dark matter.

The dataset is the first obtained by the PandaX-4T experiment at the China Jinping Underground Laboratory. The PandaX team searched this data for evidence of a beyond-the-standard-model interaction in which a fermionic dark matter particle is absorbed by the nucleus of a xenon atom. After the absorption, the xenon nucleus should recoil while emitting either a neutrino or an antineutrino. The interaction should also cause an energy deposition in the form of photons and electrons, which would register on photodetectors at the ends of the tank. Unlike the scattering of WIMPs, which is predicted to produce a broad-spectrum energy deposition, the absorption by nuclei of fermionic dark matter particles should deposit energy only in a narrow range.

The data collected so far represent the equivalent of exposing 0.6 tons of liquid xenon to hypothetical fermionic dark matter for one year. When PandaX-4T concludes in 2025, it will have achieved a cumulative exposure 10 times greater, generating even stronger constraints on theory.

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Simple microparticles can beat rhythmically together, generating an oscillating electrical current that could be used to power micro-robotic devices.

MIT is an acronym for the Massachusetts Institute of Technology. It is a prestigious private research university in Cambridge, Massachusetts that was founded in 1861. It is organized into five Schools: architecture and planning; engineering; humanities, arts, and social sciences; management; and science. MIT’s impact includes many scientific breakthroughs and technological advances. Their stated goal is to make a better world through education, research, and innovation.

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All its mechanical components are now together for the first time.

Good news! The largest digital camera in the world is nearly ready to be mounted on its telescope. At the SLAC National Accelerator Laboratory, technicians are finishing up the largest digital camera in the world. The camera will be shipped to Chile and mounted on a telescope located in the Andes. The project was started a couple of years ago.

Even though the camera isn’t finished yet, all of its mechanical parts have now, for the first time, been assembled into a visually appealing framework.

Jacqueline ramseyer orrell/slac national accelerator laboratory.

At the SLAC National Accelerator Laboratory, technicians are finishing up the largest digital camera in the world. The camera will be shipped to Chile and mounted on a telescope located in the Andes. The project was started a couple of years ago.

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Long-Lived Coherent Quantum States in a Superconducting Device for Quantum Information Technology

Scientists have been able to demonstrate for the first time that large numbers of quantum bits, or qubits, can be tuned to interact with each other while maintaining coherence for an unprecedentedly long time, in a programmable, solid-state superconducting processor. This breakthrough was made by researchers from Arizona State University and Zhejiang University in China, along with two theorists from the United Kingdom.

Previously, this was only possible in Rydberg atom.

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A series of buzzing, bee-like “loop-currents” could explain a recently discovered, never-before-seen phenomenon in a type of quantum material. The findings from researchers at the University of Colorado Boulder may one day help engineers to develop new kinds of devices, such as quantum sensors or the quantum equivalent of computer memory storage devices.

The quantum material in question is known by the chemical formula Mn3Si2Te6. But you could also call it “” because its manganese and tellurium atoms form a network of interlocking octahedra that look like the cells in a beehive.

Physicist Gang Cao and his colleagues at CU Boulder synthesized this molecular beehive in their lab in 2020, and they were in for a surprise: Under most circumstances, the material behaved a lot like an insulator. In other words, it didn’t allow electric currents to pass through it easily. When they exposed the honeycomb to magnetic fields in a certain way, however, it suddenly became millions of times less resistant to currents. It was almost as if the material had morphed from rubber into metal.

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A mechanism for preventing destructive instabilities in magnetically confined plasmas provides a new way for scientists to operate future nuclear-fusion reactors.

All magnetically confined plasmas naturally develop instabilities, regions where small perturbations grow rapidly [1]. Scientists have been looking for ways to prevent instabilities in a tokamak—a leading candidate for a fusion reactor—because the instabilities can cause substantial damage to the tokamak’s walls. Now Georg Harrer at the Vienna University of Technology and his colleagues have shown how these destructive instabilities can be avoided by adjusting the properties of the plasma and its confining magnetic field [2]. The researchers’ findings offer a fresh approach to running future fusion reactors.

A tokamak uses a powerful magnetic field to confine fusion fuel in the form of a plasma (a highly ionized gas) that is shaped like a ring donut. Instabilities that originate at the plasma edge (the “glaze” of the donut) are called edge-localized modes (ELMs) [3]. ELMs transport heat and particles along magnetic-field lines, moving them from the well-confined plasma core (the “filling” of the donut) to the divertor—a region of the tokamak’s walls. ELMs come in various sizes and frequencies (repetition rates). Their size, expressed as a percentage of the energy stored in the plasma core, strongly influences how much heat and how many particles will be deposited by each ELM in the divertor.

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Circa 2014 face_with_colon_three

A liquid hard drive containing a suspension of nanoparticles could be used to store impressive amounts of data: 1 terabyte per tablespoon.

Researchers from the University of Michigan and New York University have been simulating wet information storage techniques which uses clusters of nanoparticles suspended in liquid. These clusters of particles can store more data than conventional computer bits which have just two storage states: 0 and 1. The clusters of particles work a bit like Rubik’s Cubes to reconfigure in different ways to represent different storage states. A 12-particle memory cluster connected to a central sphere can have almost eight million unique states, which is equivalent to 2.86 bytes of data.

The system works by having nanoparticles attached to a central sphere. When the sphere is small, the outer particles trap each other into place, storing data. If the sphere is a bit larger, the particles can be reconfigured to store different information. The team created a cluster involving four particles on a central sphere — all made of polymers. By heating the liquid up, the spheres expand and the particles can rearrange themselves in predictable ways. Although the four-particle clusters have only two distinguishable configurations (i.e. like a regular bit), the plan is create clusters with many more particles.

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