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Category: particle physics – Page 9

Cooling liquids reveal self-limiting particle clusters behind glass transition

Before diving into the mystery of glass, theoretical physicist Corentin Laudicina takes us back to high school physics for a moment. Although he has spent years studying exactly what happens in a material during the glass transition, he also understands that his research is not the easiest thing to explain off the cuff at the cafeteria table.

According to school textbooks, matter can exist in three different states: gas, liquid and solid. Think of water vapor, liquid water and ice. The molecules that make up the material are the same, but the way they can move differs greatly, Laudicina explains.

He pulls out his dissertation and shows a figure from the introductory chapter. “The higher the temperature, the more freely the molecules can move. In a solid, they are arranged in a crystal lattice—in a fixed position, at a fixed distance from one another—but in a liquid, they can move without having a fixed position relative to each other. In the gas phase, those movements are even freer.”

Jupiter uses a surprisingly complex system to fend off particles from the sun

A University of Iowa-led research team has reported in a new study the most detailed observations to date of the bow shock at Jupiter, our solar system’s gas giant. The findings from NASA’s Juno mission reveal key differences between Jupiter’s bow shock and Earth’s. They also may lead to a better understanding of the physics of how shocks function in even more powerful energy releases, such as those from dying stars. The research is published in Nature Communications.

The bow shock is an invisible boundary between the sun and a planet’s magnetic field. It is the first line of defense against the supersonic burst of energetic particles from the sun known as the solar wind.

On Earth, the bow shock is important because it marks the point where the solar wind is slowed, heated and then deflected around Earth. If that didn’t happen, our planet would be bombarded by the solar wind, and those harmful particles could reach our atmosphere and make Earth less safe for life.

New ligand design balances radical generation and catalyst regeneration for challenging chemical reactions

Radicals, atoms or molecules that readily react with other substances to form new bonds, are useful tools for building complex substances such as pharmaceuticals. But even when a radical is generated efficiently, the reaction cannot continue unless the catalyst returns to its original state.

A KAIST research team has developed a new strategy that balances radical generation and catalyst regeneration, broadening the possibility of using substrates that are difficult to activate to synthesize complex molecules needed for pharmaceuticals and other applications.

The research team led by Professor Sarah Yunmi Lee of the Department of Chemistry developed a method that uses a ligand, a molecule that attaches to a metal catalyst and controls its properties, to effectively regulate the process by which a copper catalyst generates a radical and then returns to its original state.

Ferroelectric material that’s stable at near-atomic thickness reveals new route to low-power electronics

Electronics engineers worldwide have been trying to develop increasingly smaller components that can store and process information while consuming less energy. Ferroelectric materials, which possess spontaneous electrical polarization that can be reversed by an externally applied electric field, have proved promising for the development of denser, more energy-efficient memories and other miniaturized electronic components.

Despite their potential, shrinking these materials to produce ultrathin films that are just a few atoms thick often alters some of their properties and characteristics. Specifically, their internal polarization can become unstable at these scales, and switching it often requires relatively high voltages.

Researchers at Westlake University and Zhejiang University recently showed that gallium oxide (Ga₂O₃) could become ferroelectric at near-atomic thickness, retain stable polarization and switch between its polarization states at a relatively low voltage of 0.8 volts. Their paper, published in Nature Electronics, highlights the potential of this material for the development of compact, nonvolatile memories, small sensors and other low-power electronic components.

Scientists discover a strange new form of ice that could help explain the interiors of Neptune and Uranus

Scientists have discovered that there is ice deep inside planets like Neptune and Uranus and want to find out what form it takes and how it behaves. They cannot dig for it and transport it all the way back to Earth, so they do the next best thing: recreate those extreme conditions in the lab.

That’s exactly what a team of scientists led by Alexis Forestier from the CEA, France’s Alternative Energies and Atomic Energy Commission, did. What they discovered could help us better understand the strange magnetic fields and deep interior layers of these distant worlds.

The weird world of hot ice On those planets, ice is not like the frozen cubes you put into a cold drink. It enters a weird state known as superionic ice because of the immense heat and pressure it is under. In this exotic phase, oxygen atoms lock into a solid grid while hydrogen nuclei flow freely through it like a liquid, allowing it to conduct electricity. Scientists already knew this hot, conducting ice existed, but they did not know what specific crystal shapes it formed.

Tightly guided atoms could enable low power quantum navigation when GPS fails

Within tiny halos of light clinging to a vanishingly thin wisp of optical fiber, scientist Jongmin Lee guides atoms like marbles through a narrow pipe. Rock the fiber and the atoms shift side by side; they just don’t fall off. But don’t be deceived by the seemingly delicate nature of his experiment. Lee is exploring how to measure motion precisely in rough-and-tumble environments.

A quantum sensing scientist at Sandia National Laboratories, Lee is an expert in a type of motion sensor called an atom interferometer. In a lab, this device uses quantum mechanics to obtain exquisitely accurate measurements. Lee and his team are working toward building an extremely small, low-power version for field use—small enough to fit on a specialized type of microchip called a photonic integrated circuit.

Their latest results were published in the journal AVS Quantum Science, where the team reported trapping cesium atoms on a fiber only 420 nanometers in diameter with just 5 milliwatts of optical power—about 2,000 times less power than an LED bulb uses. With just 150 nanowatts, the researchers can also take measurements that mimic atom interferometry.

Physicists extend the search for quantum black holes at the LHC

Physicists at UC Santa Barbara have extended the search for evidence of microscopic black holes produced at the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN). The formation of these tiny, fleeting objects at the LHC represents one way theorists have sought to resolve anomalies in our understanding of the basic structure of spacetime, while the method used to look for them demonstrates a new way of searching for new particles.

“Had we found evidence, we could have begun to directly study quantum gravity,” said Tamas Vami, a researcher in the Compact Muon Solenoid (CMS) experiment who is conducting his postdoctoral work under the guidance of UCSB physics professor Joe Incandela. “It’s a step toward unifying all of the known fundamental forces, which has been a goal of physicists for more than a century.”

But a null result does not make for a fruitless search, said Incandela Lab graduate student researcher Danyi Zhang. Quite the opposite.

Stacked 2D materials reveal room-temperature multiferroicity and voltage-controlled magnetism

Multiferroics are materials that simultaneously exhibit two or more ferroic orders—stable arrangements of physical properties that can be switched using an external stimulus. These materials could be highly advantageous for the development of various technologies, including non-volatile, low-power memory devices, spintronic devices, miniaturized electronics, neuromorphic hardware, sensors and magnetoelectric devices.

The key advantage of multiferroics is that their different ferroic orders can be coupled, for instance allowing engineers to alter magnetic behavior using an electric voltage. Despite their promise, synthesizing multiferroics that are stable, ultrathin and controllable at room temperature has so far proved challenging.

Researchers at the University of Maryland and other institutes recently demonstrated an approach for creating van der Waals heterostructures that exhibit multiferroicity at room temperature.

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