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Category: particle physics – Page 191

For many, the word “crystals” conjures images of shimmering suncatchers that create a prism of rainbow colors or semi-transparent stones thought to possess healing abilities. But in the realm of science and engineering, crystals take on a more technical definition. They’re perceived as materials whose components – be it atoms, molecules, or nanoparticles –are arranged regularly in space. In other words, crystals are defined by the regular arrangement of their constituents. Familiar examples include diamonds, table salt, and sugar cubes.

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Magnetic fields are common throughout the universe but incredibly challenging to study. They don’t directly emit or reflect light, and light from all along the electromagnetic spectrum remains the primary purveyor of astrophysical data. Instead, researchers have had to find the equivalent of cosmic iron filings—matter in galaxies that is sensitive to magnetic fields and also emits light marked by the fields’ structure and intensity.

In a new study published in The Astrophysical Journal, several Stanford astrophysicists have studied infrared signals from just such a material—magnetically aligned dust grains embedded in the cold, dense clouds of star-forming regions. A comparison to light from cosmic ray electrons that has been marked by magnetic fields in warmer, more diffuse material showed surprising differences in the measured magnetic fields of .

Stanford astrophysicist and member of the Kavli Institute for Particle Acceleration and Cosmology (KIPAC) Enrique Lopez-Rodriguez explains the differences and what they could mean for galactic growth and evolution.

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Theoretical physicists have a lot in common with lawyers. Both spend a lot of time looking for loopholes and inconsistencies in the rules that might be exploited somehow.

Valeri P. Frolov and Andrei Zelnikov from the University of Alberta in Canada and Pavel Krtouš from Charles University in Prague probably couldn’t get you out of a traffic fine, but they may have uncovered enough wiggle room in the laws of physics to send you back in time to make sure you didn’t speed through that school zone in the first place.

Shortcuts through spacetime known as wormholes aren’t recognized features of the cosmos. But for the better part of a century, scientists have wondered if the weft and warp instructed by relativity prescribe ways for quantum ripples – or even entire particles – to break free of their locality.

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An international team of researchers, including members from the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), has succeeded in a proof-of-principle experiment to verify strong-field quantum electrodynamics within exotic atoms, according to a recent study published in Physical Review Letters.

Physical Review Letters (PRL) is a peer-reviewed scientific journal published by the American Physical Society. It is one of the most prestigious and influential journals in physics, with a high impact factor and a reputation for publishing groundbreaking research in all areas of physics, from particle physics to condensed matter physics and beyond. PRL is known for its rigorous standards and short article format, with a maximum length of four pages, making it an important venue for rapid communication of new findings and ideas in the physics community.

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Physicists at Harvard University in the US have created a novel strongly interacting quantum liquid known as a Laughlin state in a gas of ultracold atoms for the first time. The state, which is an example of a fractional quantum Hall (FQH) state, had previously been seen in condensed-matter systems and in photons, but observations in atoms had been elusive due to stringent experimental requirements. Because atomic systems are simpler than their condensed-matter counterparts, the result could lead to fresh insights into fundamental physics.

“Some of the most intriguing phenomena in condensed-matter physics emerge when you confine electrons in two dimensions and apply a strong magnetic field,” explains Julian Léonard, a postdoctoral researcher in the Rubidium Lab at Harvard and the lead author of a paper in Nature on the new work. “For example, the particles can behave collectively as if they have a charge that is only a fraction of the elementary charge – something that does not occur anywhere else in nature and is even ruled out by the Standard Model for all fundamental particles.”

The way in which such fractional charges arise is still not fully understood because it is difficult to study solid-state systems at an atomic scale. This is why it is so desirable to study the behaviour of FQHs in synthetic quantum systems such as cold atoms, which act as quantum simulators for more complex condensed-matter phenomena.

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The future of electronics will be based on novel kinds of materials. Sometimes, however, the naturally occurring topology of atoms makes it difficult for new physical effects to be created. To tackle this problem, researchers at the University of Zurich have now successfully designed superconductors one atom at a time, creating new states of matter.

What will the computer of the future look like? How will it work? The search for answers to these questions is a major driver of basic physical research. There are several possible scenarios, ranging from the further development of classical electronics to neuromorphic computing and quantum computers.

The common element in all these approaches is that they are based on novel physical effects, some of which have so far only been predicted in theory. Researchers go to great lengths and use state-of-the-art equipment in their quest for new quantum materials that will enable them to create such effects. But what if there are no suitable materials that occur naturally?

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Japanese scientists have discovered a compound, ethylammonium lead iodide, which can store and release ammonia safely and efficiently. This finding holds potential for ammonia’s role as a carbon-free hydrogen carrier, contributing to the transition towards a decarbonized society.

Researchers at the RIKEN Center for Emergent Matter Science (CEMS) in Japan have discovered a compound that uses a chemical reaction to store ammonia, potentially offering a safer and easier way to store this important chemical. This discovery, published in the Journal of the American Chemical Society on July 10, makes it possible not only to safely and conveniently store ammonia, but also the important hydrogen is carries. This finding should help lead the way to a decarbonized society with a practical hydrogen economy.

For society to make the switch from carbon-based to hydrogen-based energy, we need a safe way to store and transport hydrogen, which by itself is highly combustible. One way to do this is to store it as part of another molecule and extract it as needed. Ammonia, chemically written as NH3, makes a good hydrogen carrier because three hydrogen atoms are packed into each molecule, with almost 20% of ammonia being hydrogen by weight.

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The images shed light on how electrons form superconducting pairs that glide through materials without friction.

When your laptop or smartphone heats up, it’s due to energy that’s lost in translation. The same goes for power lines that transmit electricity between cities. In fact, around 10 percent of the generated energy is lost in the transmission of electricity. That’s because the electrons that carry electric charge do so as free agents, bumping and grazing against other electrons as they move collectively through power cords and transmission lines. All this jostling generates friction, and, ultimately, heat.

But when electrons pair up, they can rise above the fray and glide through a material without friction. This “superconducting” behavior occurs in a range of materials, though at ultracold temperatures. If these materials can be made to superconduct closer to room temperature, they could pave the way for zero-loss devices, such as heat-free laptops and phones, and ultra-efficient power lines. But first, scientists will have to understand how electrons pair up in the first place.

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“A phonon represents the collective motion of an astronomical number of atoms,” Cleland says. “And they all have to work together in order to obey quantum mechanics. There was this question in the back of my mind, will this really work? We tried it, and it’s kind of amazing, but it really does work.”

Splitting a phonon

The team created single phonons as propagating wavepackets on the surface of a lithium niobate chip. The phonons were created and detected using two superconducting qubits, which were located on a separate chip, and coupled to the lithium niobate chip through the air. The two superconducting qubits were located either of the chip, with a two-millimetre-long channel between them hosting the travelling phonons.

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The quantum nature of interactions between elementary particles allows drawing non-trivial conclusions even from processes as simple as elastic scattering. The ATLAS experiment at the LHC accelerator reports the measurement of fundamental properties of strong interactions between protons at ultra-high energies.

The physics of billiard ball collisions is taught from early school years. In a good approximation, these collisions are elastic, where both momentum and energy are conserved. The scattering angle depends on how central the collision was (this is often quantified by the impact parameter value—the distance between the centers of the balls in a plane perpendicular to the motion). In the case of a small impact parameter, which corresponds to a highly central collision, the scattering angles are large. As the impact parameter increases, the scattering angle decreases.

In , we also deal with elastic collisions, when two particles collide, maintaining their identities, and scatter a certain angle to their original direction of motion. Here, we also have a relationship between the collision parameter and the scattering angle. By measuring the scattering angles, we gain information about the spatial structure of the colliding particles and the properties of their interactions.

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