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Category: particle physics

A novel, high-resolution fluorescence imaging technique reveals a pattern, known as a Pauli crystal, that can emerge in a cloud of trapped, noninteracting fermions.

Bring two particles together and, in general, they will interact. For example, two electrons will repel each other through electrostatic forces, or two atoms may form a molecule through electrostatic and van der Waals forces. Noninteracting particles, however, can also affect another’s behavior in a way that depends on the spin of both particles. In particular, fermionic particles, which have half-integer spin, obey the Pauli exclusion principle, which states that two fermions can never occupy the same quantum state. Two electrons in an atom, for instance, can never occupy the same quantum state. As a result, noninteracting particles can form self-organized structures. However, these structures, called Pauli crystals, have not been previously observed. Now using ultracold atoms, Marvin Holten from the University of Heidelberg, Germany, and colleagues have experimentally realized and imaged a Pauli crystal [1].

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The tool next examines how one protein’s amino acids interact with another within the same protein, for example, by examining the distance between two distant building blocks. It’s like looking at your hands and feet fully stretched out, versus in a backbend measuring the distance between those extremities as you “fold” into a yoga pose.

Finally, the third track looks at 3D coordinates of each atom that makes up a protein building block—kind of like mapping the studs on a Lego block—to compile the final 3D structure. The network then bounces back and forth between these tracks, so that one output can update another track.

The end results came close to those of DeepMind’s tool, AlphaFold2, which matched the gold standard of structures obtained from experiments. Although RoseTTAFold wasn’t as accurate as AlphaFold2, it seemingly required much less time and energy. For a simple protein, the algorithm was able to solve the structure using a gaming computer in about 10 minutes.

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One of the most important open questions in science is how our consciousness is established. In the 1990s, long before winning the 2020 Nobel Prize in Physics for his prediction of black holes, physicist Roger Penrose teamed up with anaesthesiologist Stuart Hameroff to propose an ambitious answer.

They claimed that the brain’s neuronal system forms an intricate network and that the consciousness this produces should obey the rules of quantum mechanics – the theory that determines how tiny particles like electrons move around. This, they argue, could explain the mysterious complexity of human consciousness.

Penrose and Hameroff were met with incredulity. Quantum mechanical laws are usually only found to apply at very low temperatures. Quantum computers, for example, currently operate at around -272°C. At higher temperatures, classical mechanics takes over. Since our body works at room temperature, you would expect it to be governed by the classical laws of physics. For this reason, the quantum consciousness theory has been dismissed outright by many scientists – though others are persuaded supporters.

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Circa 1999 could lead to a sorta room temperature hydrogen fill up.

Masses of single-walled carbon nanotubes (SWNTs) with a large mean diameter of about 1.85 nanometers, synthesized by a semicontinuous hydrogen arc discharge method, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states. A hydrogen storage capacity of 4.2 weight percent, or a hydrogen to carbon atom ratio of 0.52, was achieved reproducibly at room temperature under a modestly high pressure (about 10 megapascal) for a SWNT sample of about 500 milligram weight that was soaked in hydrochloric acid and then heat-treated in vacuum. Moreover, 78.3 percent of the adsorbed hydrogen (3.3 weight percent) could be released under ambient pressure at room temperature, while the release of the residual stored hydrogen (0.9 weight percent) required some heating of the sample.

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Experiments now online or being built in Japan, South Korea, Italy, Canada and the United States are an order of magnitude more sensitive than the previous generation, and planned future detectors would improve on that by another two orders of magnitude (see ‘Experiments around the world’). In 2015, an advisory committee to the US Department of Energy identified such a project as a priority and a commitment to fund an experiment to detect Majorana neutrinos — estimated to cost up to/around US$250 million — is thought to be imminent.

The search for exotic ‘Majorana’ particles that could solve a big antimatter mystery is ramping up around the world.

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The Juno Waves instrument “listened” to the radio emissions from Jupiter’s immense magnetic field to find their precise locations.

By listening to the rain of electrons flowing onto Jupiter from its intensely volcanic moon Io, researchers using NASA’s Juno spacecraft have found what triggers the powerful radio emissions within the monster planet’s gigantic magnetic field. The new result sheds light on the behavior of the enormous magnetic fields generated by gas-giant planets like Jupiter.

Jupiter has the largest, most powerful magnetic field of all the planets in our solar system, with a strength at its source about 20000 times stronger than Earth’s. It is buffeted by the , a stream of electrically charged particles and magnetic fields constantly blowing from the Sun. Depending on how hard the solar wind blows, Jupiter’s magnetic field can extend outward as much as two million miles (3.2 million kilometers) toward the Sun and stretch more than 600 million miles (over 965 million kilometers) away from the Sun, as far as Saturn’s orbit.

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Researchers at ETH Zurich have trapped a tiny sphere measuring a hundred nanometres using laser light and slowed down its motion to the lowest quantum mechanical state. This technique could help researchers to study quantum effects in macroscopic objects and build extremely sensitive sensors.

Why can atoms or elementary particles behave like waves according to , which allows them to be in several places at the same time? And why does everything we see around us obviously obey the laws of classical physics, where such a phenomenon is impossible? In recent years, researchers have coaxed larger and larger objects into behaving quantum mechanically. One consequence of this is that, when passing through a double slit, these objects form an that is characteristic of waves.

Up to now, this could be achieved with molecules consisting of a few thousand atoms. However, physicists hope one day to be able to observe such quantum effects with properly . Lukas Novotny, professor of photonics, and his collaborators at the Department of Information Technology and Electrical Engineering at ETH Zurich have now made a crucial step in that direction. Their results were recently published in the scientific journal Nature.

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Quantum mechanics deals with the behavior of the Universe at the super-small scale: atoms and subatomic particles that operate in ways that classical physics can’t explain. In order to explore this tension between the quantum and the classical, scientists are attempting to get larger and larger objects to behave in a quantum-like way.

In the case of this particular study, the object in question is a tiny glass nanosphere, 100 nanometers in diameter – about a thousand times smaller than the thickness of a human hair. To our minds that’s very, very small, but in terms of quantum physics, it’s actually rather huge, made up to 10 million atoms.

Pushing such a nanosphere into the realm of quantum mechanics is actually a huge achievement, and yet that’s exactly what physicists have now accomplished.

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A collaborative research team, led by the University of Liverpool, has discovered a new inorganic material with the lowest thermal conductivity ever reported. This discovery paves the way for the development of new thermoelectric materials that will be critical for a sustainable society.

Reported in the journal Science, this discovery represents a breakthrough in the control of heat flow at the atomic scale, achieved by materials design. It offers fundamental new insights into the management of energy. The new understanding will accelerate the development of new materials for converting waste heat to power and for the efficient use of fuels.

The research team, led by Professor Matt Rosseinsky at the University’s Department of Chemistry and Materials Innovation Factory and Dr. Jon Alaria at the University’s Department of Physics and Stephenson Institute for Renewable Energy, designed and synthesized the new material so that it combined two different arrangements of atoms that were each found to slow down the speed at which heat moves through the structure of a solid.

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