Lifeboat Foundation

The physicists Alain Aspect, John Clauser and Anton Zeilinger have won the 2022 Nobel Prize in Physics for experiments that proved the profoundly strange quantum nature of reality. Their experiments collectively established the existence of a bizarre quantum phenomenon known as entanglement, where two widely separated particles appear to share information despite having no conceivable way of communicating.

Entanglement lay at the heart of a fiery clash in the 1930s between physics titans Albert Einstein on the one hand and Niels Bohr and Erwin Schrödinger on the other about how the universe operates at a fundamental level. Einstein believed all aspects of reality should have a concrete and fully knowable existence. All objects — from the moon to a photon of light — should have precisely defined properties that can be discovered through measurement. Bohr, Schrödinger and other proponents of the nascent quantum mechanics, however, were finding that reality appeared to be fundamentally uncertain; a particle does not possess certain properties until the moment of measurement.

Entanglement emerged as a decisive way to distinguish between these two possible versions of reality. The physicist John Bell proposed a decisive thought experiment that was later realized in various experimental forms by Aspect and Clauser. The work proved Schrödinger right. Quantum mechanics was the operating system of the universe.

With the aid of some sea slugs, University of Nebraska–Lincoln chemists have discovered that one of the smallest conceivable tweaks to a biomolecule can elicit one of the grandest conceivable consequences: directing the activation of neurons.

Their discovery came from investigating peptides, the short chains of amino acids that can transmit signals among cells, including neurons, while populating the central nervous systems and bloodstreams of most animals. Like many other molecules, an amino acid in a peptide can adopt one of two forms that feature the same atoms, with the same connectivity, but in mirror-image orientations: L and D.

Chemists often think of those two orientations as the left and right hands of a molecule. The L orientation is by far the more common in peptides, to the point of being considered the default. But when enzymes do flip an L to a D, the seemingly minor about-face can turn, say, a potentially therapeutic molecule into a toxic one, or vice versa.

Quantum computing systems have the potential to outperform classical computers on some tasks, helping to solve complex real-world problems in shorter times. Research teams worldwide have thus been trying to realize this quantum advantage over traditional computers, by creating and testing different quantum systems.

Researchers at Tsinghua University recently developed a new programmable quantum phononic processor with trapped ions. This processor, introduced in a paper in Nature Physics, could be easier to scale up in size than other previously proposed photonic quantum processors, which could ultimately enable better performances on complex problems.

“Originally, we were interested in the proposal of Scott Aaronson and others about Boson sampling, which might show the quantum advantages of simple linear optics and photons,” Kihwan Kim, one of the researchers who carried out the study, told Phys.org. “We were wondering if it is possible to realize it with the phonons in a trapped ion system.”

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.