Experimental physicists take step toward understanding natural quantum systems

Physics graduate student Frank Corapi adjusts the alignment of a laser beam in the Ultracold Atoms Lab at U of T - "Suppose you knew everything there was to know about a water molecule - the chemical formula, the bond angle, etc.," says experimental physicist Joseph Thywissen. "You might know everything about the molecule, but still not know there are waves on the ocean - much less how to surf them," he says. "That's because when you put a bunch of molecules together, they behave in a way you probably cannot anticipate." Thywissen is a professor in the University of Toronto's department of physics in the Faculty of Arts & Science and a member of the Centre for Quantum Information & Quantum Control. He is describing the concept in physics known as emergence: the relationship between the behaviour and characteristics of individual particles and large numbers of those particles. Thywissen and his collaborators have taken a first step toward understanding the transition from "one-to-many" particles by studying not one, not many, but two isolated, interacting particles - in this case potassium atoms. The result is described in a paper  published recently in the journal  Nature . A team that included experimental physicists from University of Toronto and theoretical physicists from the University of Colorado (UC) measured the strength of a type of interaction - known as "p-wave interactions" - between two potassium atoms and found the result confirms a longstanding prediction.