When one atom first meets another, the precise nature of that interaction can determine much about what kinds of physical properties and behaviours will emerge.
In a paper published today in Nature Physics, a team led by U of T physicist Joseph Thywissen reported their discovery of a new set of rules related to one particular type of atomic-pair interaction. The researchers study interactions between atoms that have been cooled close to absolute zero.
“Ultracold atoms are the stem cells of materials science,” says Thywissen, a Professor of Physics at the University of Toronto and also a Fellow of the Quantum Materials program at the Canadian Institute for Advanced Research. “Just as a stem cell can become a fingernail or a heart cell depending on its context, ultracold atoms can become metals, insulators, superfluids or other types of materials.”
In collaboration with theorists Shizhong Zhang of Hong Kong University and Zhenhua Yu of Tsinghua University, the Toronto experimentalists have been studying “p-wave interactions.” The term “p-wave” refers to the degree to which two atoms twirl around one another – a phenomenon physicists refer to as “angular momentum.”
Researchers study these interactions in a highly controlled environment, coaxing a few hundred thousand gas atoms into a “trap,” and cooling them to about -273 Celsius.