Particle physics laboratory

Scientists create strange quantum ‘domain walls’ in the lab

Researchers at the University of Chicago have discovered how to create and manipulate a quantum phenomenon known as the “domain wall” – represented in this image by the lighter line between two groups of atoms. (Image adapted and color added from experiment data.) Credit: Illustration by Kai-Xuan Yao

Mastered for the first time, the quantum phenomenon could suggest avenues for technology.

University of Chicago scientists have been able to create a new type of quantum object in the laboratory at will: “domain walls”.

This discovery can help researchers better understand exotic quantum particles and could suggest avenues for new technologies in the future, such as quantum electronics or quantum memory.

Published on February 2, 2022 in the review Nature, the research was conducted in the laboratory of Professor Cheng Chin, who studies new quantum systems and the physics behind them. In one of their experiments, the UChicago scientists noticed an intriguing occurrence in atoms at extremely low temperatures. Under the right conditions, groups of atoms can separate into domains, and a “wall” forms at the junction where they met. This domain wall behaved like an independent quantum object.

“It’s a bit like a sand dune in the desert – it’s made up of sand, but the dune acts like an object that behaves differently than individual grains of sand,” said Ph.D. student Kai-Xuan Yao. , the first author of the study.

Scientists had glimpsed these domain walls in quantum materials, but previously could not reliably generate and analyze them. Once UChicago physicists created the recipe for making and studying the walls up close, they observed some surprising behaviors.

Scientists are interested in cataloging these behaviors in part because they may become the basis for future technology.

“We have a lot of experience in controlling atoms,” said Chin, who is appointed to the Department of Physics, the James Franck Institute and the Enrico Fermi Institute. “We know that if you push the atoms to the right, they will move to the right. But here, if you push the domain wall to the right, it moves to the left.

These domain walls are part of a class known as “emergent” phenomena, meaning that they appear to follow new laws of physics due to the collective action of many particles.

Chin’s lab studies these emergent phenomena, believing they can shed light on a body of laws called dynamic gauge theory, which describes other emergent phenomena in materials as well as in the early universe; the same phenomena probably held the first particles together as they clumped together to form galaxies, stars and planets.

Breakthroughs in this area could also enable new quantum technology. Scientists are interested in cataloging these behaviors in part because they may become the basis for future technology – for example, the basis of modern GPS comes from scientists in the 1950s trying to test Einstein’s theory of relativity .

“There may be applications for this phenomenon in terms of making programmable quantum materials or quantum information processors – it can be used to create a more robust way to store quantum information or enable new functions in materials” , Chin said. “But before you can find out, the first step is to figure out how to control them.”

Reference: “Dynamics of domain walls in Bose–Einstein condensates with synthetic gauge fields” by Kai-Xuan Yao, Zhendong Zhang & Cheng Chin, February 2, 2022, Nature.
DOI: 10.1038/s41586-021-04250-3

The third author of the article was Ph.D. student Zhendong Zhang.

Funding: National Science Foundation, Army Research Office, US Department of Energy Office of Basic Sciences.