Lifeboat Foundation

Polarons are localized quasiparticles that result from the interaction between fermionic particles and bosonic fields. Specifically, polarons are formed when individual electrons in crystals distort their surrounding atomic lattice, producing composite objects that behave more like a massive particles than electron waves.

Feliciano Giustino and Weng Hong Sio, two researchers at the University of Texas at Austin, recently carried out a study investigating the processes underpinning the formation of polarons in 2D materials. Their paper, published in Nature Physics, outlines some fundamental mechanisms associated with these particles’ formation that had not been identified in previous works.

“Back in 2019, we developed a new theoretical and computational framework to study polarons,” Feliciano Giustino, one of the researchers who carried out the study, told Phys.org. “One thing that caught our attention is that many experimental papers discuss polarons in 3D bulk materials, but we could find only a couple of papers reporting observations of these particles in 2D. So, we were wondering whether this is just a coincidence, or else polarons in 2D are more rare or more elusive than in 3D, and our recent paper addresses this question.”

For their new study, the researchers aimed to understand how quantum correlations inside a source material, be it a gas or a mineral, would impact the quantum properties of the light bursts coming out, if at all. “High harmonic generation is a very important area. And still, until recently, it was described by a classical picture of light,” Kaminer says.

In quantum mechanics, figuring out what’s going on with more than a few particles at the same time is notoriously difficult. Kaminer and Alexey Gorlach, a graduate student in his lab, used their COVID-imposed isolation to try to make progress on a fully quantum description of light emitted in high harmonics. “It’s really crazy; Alexey built a super complex mathematical description on a scale that we’ve never had before,” Kaminer says.

Next, to fully incorporate the quantum properties of the material used to generate this light, Kaminer and Gorlach teamed up with Andrea Pizzi, then a graduate student at the University of Cambridge and now a postdoctoral fellow at Harvard University.

The team’s measurement of the proton’s radius was 0.73 femtometer, even smaller than the 0.84-femtometer electric charge radius. In either case, it is almost 10,000 times smaller than a hydrogen atom.

To be clear, this apparent 13 percent shrinkage is not a blow to the electric charge radius measurements and not as shocking as it may seem. The two measurements are complementary and work together to offer a big picture view of the little proton. Because they measure different distributions of matter, the discrepancy does not challenge our understanding of the proton the same way its previous 4 percent shrinkage did. Instead it adds to that understanding.

“The thing that makes this measurement really interesting is not whether or not it agrees with the electron measurements of the electromagnetic proton radius but the fact that it didn’t have to agree at all,” says Deborah Harris, co-spokesperson for the MINERvA experiment. This is because the way neutrinos interact with up quarks versus down quarks is very different from how quarks interact with electrons. Instead of an electromagnetic interaction, neutrinos interact via a different force called the weak force. (But don’t let its name fool you—the weak force is quite strong across subatomic distances!)

With each of these splittings, the universe completely remolded itself. New particles arose to replace ones that could exist only in extreme conditions previously. The fundamental quantum fields of space-time that dictate how particles and forces interact with each other reconfigured themselves. We do not know how smoothly or roughly these phase transitions took place, but it’s perfectly possible that with each splitting, the universe settled into multiple identities at once.

This fracturing isn’t as exotic as it sounds. It happens with all kinds of phase transitions, like water turning into ice. Different patches of water can form ice molecules with different orientations. No matter what, all the water turns into ice, but different domains can have differing molecular arrangements. Where those domains meet walls, or imperfections, fracturing will appear.

Physicists are especially interested in the so-called GUT phase transition of our universe. GUT is short for “grand unified theory,” a hypothetical model of physics that merges the strong nuclear force with electromagnetism and the weak nuclear force. These theories are just beyond the reach of current experiments, so physicists and astronomers turn to the conditions of the early universe to study this important transition.

A new algorithm can organize hundreds of atoms into pristine patterns—including a honeycomb lattice, a fractal called a Sierpiński triangle, and a lion’s head.

Strongly correlated systems are systems made of particles that strongly interact with one another, to such an extent that their individual behavior depends on the behavior of all other particles in the system. In states that are far from equilibrium, these systems can sometimes give rise to fascinating and unexpected physical phenomena, such as many-body localization.

Many-body localization occurs when a system made of interacting particles fails to reach thermal equilibrium even at high temperatures. In many-body localized systems, particles thus remain in a state of non-equilibrium for long periods of time, even when a lot of energy is flowing through them.

Theoretical predictions suggest that the instability of the many-body localized phase is caused by small thermal inclusions in the strongly interacting system that act as a bath. These inclusions prompt the delocalization of the entire system, through a mechanism that is known as avalanche propagation.

Most people only encounter turbulence as an unpleasant feature of air travel, but it’s also a notoriously complex problem for physicists and engineers. The same forces that rattle planes are swirling in a glass of water and even in the whorl of subatomic particles. Because turbulence involves interactions across a range of distances and timescales, the process is too complicated to be solved through calculation or computational modeling—there’s simply too much information involved.

Scientists have attempted to tackle the issue by studying the turbulence that occurs in superfluids, which is formed by tiny identical whirls called quantized vortices. A key question is how turbulence happens on the quantum scale and how is it linked to turbulence at larger scales.

Researchers at Aalto University have brought that goal closer with a new study of quantum wave turbulence. Their findings, published in Nature Physics, demonstrate a new understanding of how wave-like motion transfers energy from macroscopic to microscopic length scales, and their results confirm a theoretical prediction about how the energy is dissipated at small scales.

One of the first practical applications of the much-hyped but little-used quantum computing technology is now within reach, thanks to a unique approach that sidesteps the major problem of scaling up such prototypes.

The invention, by a University of Bristol physicist, who gave it the name “counterportation,” provides the first-ever practical blueprint for creating in the lab a wormhole that verifiably bridges space, as a probe into the inner workings of the universe.

By deploying a novel computing scheme, revealed in the journal Quantum Science and Technology, which harnesses the basic laws of physics, a small object can be reconstituted across space without any particles crossing. Among other things, it provides a “smoking gun” for the existence of a physical reality underpinning our most accurate description of the world.

Imagine a universe with extremely strong gravity. Stars would be able to form from very little material. They would be smaller than in our universe and live for a much shorter amount of time. But could life evolve there? It took human life billions of years to evolve on Earth under the pleasantly warm rays from the Sun after all.

Now imagine a universe with extremely weak gravity. Its matter would struggle to clump together to form stars, planets and—ultimately—living beings. It seems we are pretty lucky to have gravity that is just right for life in our universe.

This isn’t just the case for gravity. The values of many forces and particles in the universe, represented by some 30 so-called fundamental constants, all seem to line up perfectly to enable the evolution of intelligent life. But there’s no theory explaining what values the constants should have—we just have to measure them and plug their numbers into our equations to accurately describe the cosmos.