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Matching vibrations is all it takes to shut down superconductivity in a nearby crystal

The world is never really at rest. Even in a vacuum near ultracold temperatures where all classical motion should come to a halt, you’ll find quantum fluctuations. In thin, two-dimensional materials, these include random vibrations that can alter electromagnetic fields, a feature that theorists have posited could be quite useful for modifying materials.

“It’s a holy grail we’ve been searching for decades,” said Dmitri Basov, Higgins Professor of Physics at Columbia. “We believe we’ve found it.”

In a new paper published in Nature, Basov and 32 collaborators from 17 institutions came together to confirm that quantum fluctuations alone from the vacuum inside atom-thin layers of 2D materials can alter the properties of a larger nearby crystal—a theoretical possibility now experimentally realized for the first time.

New technique spots hidden defects to boost reliability of ultrathin electronics

Future devices will continue to probe the frontier of the very small, and at scales where functionality depends on mere atoms, even the tiniest flaw matters. Researchers at Rice University have shown that hard-to-spot defects in a widely used two-dimensional insulator can trap electrical charges and locally weaken the material, making it more likely to fail at lower voltages. The findings are published in Nano Letters.

“By showing practical ways to detect when and where these defects form, we help make future devices more reliable and repeatable,” said Hae Yeon Lee, an assistant professor of materials science and nanoengineering at Rice, who is a corresponding author on the study.

Building ultrathin electronics such as advanced transistors, photodetectors and quantum devices involves stacking sheets of different 2D materials on top of each other into “heterostructures.” Hexagonal boron nitride (hBN), prized for being atomically flat and chemically stable, is a common building block.

‘Solar battery’ stores sunlight for days, then releases hydrogen on demand

A new material can store energy from sunlight and convert it into hydrogen days later. The material, jointly developed by researchers from Ulm and Jena, can do this even in the dark. The process is reversible and can be reactivated several times using a pH switch. The results are published in the journal Nature Communications.

Green hydrogen is one of the most important pillars of the energy transition. It is produced from sunlight using photocatalytic processes. There are now a variety of technologies for converting and storing solar energy into chemical energy. But now, for the first time, a material that can store the energy from sunlight for several days and then release it in the form of hydrogen “at the push of a button” has been successfully developed.

“You can think of it as a combination of a solar cell and a battery at the molecular level,” explains Professor Sven Rau, who heads the Institute of Inorganic Chemistry I at Ulm University.

Energy loss triggers quantum thermal Hall-like effect at macroscopic scale

In many quantum materials—materials with unusual electrical and magnetic properties driven by quantum mechanical effects—electrons can organize themselves into Landau levels are essentially quantized energy states that form when charged particles move in a magnetic field.

This process, called Landau quantization, forces electrons into circular (i.e., cyclotron) motion. This motion ultimately produces evenly spaced Landau levels, which are known to underpin various physical phenomena, including the quantum Hall effect.

The quantum Hall effect is a quantum equivalent of the Hall effect that emerges in some two-dimensional (2D) materials at extremely low temperatures and under strong magnetic fields. This effect prompts electrical current to flow along the edges of a material with extremely low loss of energy.

What does it mean to compute? Framework maps hidden computations running inside natural dynamic systems

Some computers are easy to spot. Artificial, human-built computers like those found in smartphones and laptops are abstract dynamic systems with observable computational elements like input, output, energy cost, and logical processes. Other computers aren’t so readily recognized.

Scientists have argued that many natural dynamic systems—from cells to brains to turbulence in fluids—carry out computations, too. However, it’s not always been clear what these dynamic systems are computing, or how they might be harnessed to solve tasks, says SFI Professor David Wolpert.

Smart materials and drug delivery could exploit lipid molecules that reorganize at drying interfaces

Minor changes in moisture level can promote lipid molecules to reorganize themselves in biomaterial or biomembranes. This can affect how the skin, lungs and tear film protect us from dehydration. This new discovery from Lund University in Sweden could be the inspiration for smart materials and new drug delivery techniques.

Imagine a membrane that separates dry air from a moist interior. When moisture levels become lower, the lipid molecules organize themselves in an adaptive way—and now researchers in Lund have characterized this process.

“What surprised me was how powerful the sorting of the lipid molecules was even at small changes in the moisture level. I had not expected this based on what we know about the systems in conditions where there is no evaporation,” says Nikol Labecka, researcher in chemistry at Lund University.

A new, useful absorption limit for ultra-thin films

The applications of ultrathin, conductive films such as those made of graphene have many applications, but it’s been thought their efficacy is limited to absorbing only half of the incidental light at best. A research group in China has now shown that absorption can be as high as 82.8% at light grazing angles nearly parallel to the film. This could not only significantly improve design efficiencies but sheds light on light-matter interactions at sizes much lower than the light’s wavelength. Their work has been published in Physical Review Letters.

Graphene ultrathin films, as thin as one carbon atom (about 0.34 nanometers, 300,000 times thinner than a sheet of paper) have many applications: flexible and transparent electronics, energy storage and batteries, solar cells and photovoltaics, sensors and high-speed electronics and more, where they absorb light.

While such films allow for miniaturizing devices and reducing their weight, their extreme thinness has led to the characterization that they are limited to absorbing only half of the incoming light.

Rydberg atoms detect clear signals from a handheld radio

For the first time, a team of US researchers has used sensors containing highly excited Rydberg atoms to detect signals from an ordinary handheld radio. Through a careful approach to demodulating the incoming signals, Noah Schlossberger and colleagues at the National Institute of Standards and Technology (NIST) were able to recover audio encoded in multiple public radio channels, with promising implications for everyday uses in consumer electronics. The research has been published in Physical Review Applied.

In a Rydberg atom, a single electron is excited to an extremely high energy level, pushing it far from its host atom’s nucleus. From a distance, these atoms resemble a single electron orbiting a positively charged ion.

When any atom is exposed to an external electric field, the positions of its electrons’ energy levels shift through a process called the Stark effect. Yet in a Rydberg atom, the shift becomes far more pronounced, causing particularly striking changes in the spectral patterns produced when the atom is probed by a laser.

Tackling industry’s burdensome bubble problem

In industrial plants around the world, tiny bubbles cause big problems. Bubbles clog filters, disrupt chemical reactions, reduce throughput during biomanufacturing, and can even cause overheating in electronics and nuclear power plants. MIT Professor Kripa Varanasi has long studied methods to reduce bubble disruption.

In a new study, Varanasi, along with Ph.D. candidate Bert Vandereydt and former postdoc Saurabh Nath, have uncovered the physics behind a promising type of debubbling membrane material that is “aerophilic”—Greek for “air-loving.” The material can be used in systems of all types, allowing anyone to optimize their machine’s performance by breaking free from bubble-borne disruptions.

“We have figured out the structure of these bubble-attracting membrane materials to allow gas to evacuate in the fastest possible manner,” says Varanasi, the senior author of the study.

Why you can’t tie knots in four dimensions

We all know we live in three-dimensional space. But what does it mean when people talk about four dimensions? Is it just a bigger kind of space? Is it “space-time,” the popular idea which emerged from Einstein’s theory of relativity?

If you have wondered what four dimensions really look like, you may have come across drawings of a “four-dimensional cube.” But our brains are wired to interpret drawings on flat paper as two-or at most three-dimensional, not four-dimensional.

The almost insurmountable difficulty of visualizing the fourth dimension has inspired mathematicians, physicists, writers and even some artists for centuries. But even if we can’t quite imagine it, we can understand it.

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