Physicists at the University of Chicago have demonstrated formation of a new kind of quantum object — dubbed a ‘domain wall’ — in a Bose-Einstein condensate. Their result can help scientists better understand exotic quantum particles and could suggest avenues for new technologies in the future.
A ‘domain wall’ in this image is the lighter line between two groups of atoms. Image credit: Kai-Xuan Yao.
University of Chicago’s Professor Cheng Chin and colleagues study novel quantum systems and the physics that underlie them.
In one of their experiments, they noticed an intriguing occurrence in a Bose-Einstein condensate, a group of atoms cooled to within a hair of absolute zero.
Under the right conditions, a Bose-Einstein condensate of cesium-133 atoms segregated into domains, and a ‘wall’ formed at the junction where they met.
This domain wall behaved like an independent quantum object, according to the team.
“It’s kind of like a sand dune in the desert — it’s made up of sand, but the dune acts like an object that behaves differently from individual grains of sand,” University of Chicago Ph.D. student Kai-Xuan Yao.
Physicists had glimpsed these domain walls in quantum materials, but previously, they couldn’t reliably generate and analyze them.
Once Professor Chin’s team created the recipe to make and closely study the walls, they observed surprising behaviors.
“We have a lot of experience in controlling atoms,” Professor Chin said.
“We know if you push atoms to the right, they will move right.”
“But here, if you push the domain wall to the right, it moves left.”
These domain walls are part of a class known as emergent phenomena, which means that they appear to follow new laws of physics as a result of many particles acting together as a collective.
The authors study these phenomena, believing they can shed light on a set of laws called dynamical gauge theory, which describes other emerging phenomena in materials as well as in the early Universe.
The same phenomena likely held together the first particles as they clumped together to form galaxies, stars, and planets.
Breakthroughs in this field could also enable new quantum technology.
“There may be applications for this phenomenon in terms of making programmable quantum material or quantum information processor — it can be used to create a more robust way to store quantum information or enable new functions in materials,” Professor Chin said.
“But before we can find that out, the first step is to understand how to control them.”
The team’s work was published in the journal Nature.
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K.-X. Yao et al. 2022. Domain-wall dynamics in Bose-Einstein condensates with synthetic gauge fields. Nature 602, 68-72; doi: 10.1038/s41586-021-04250-3
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