Ultracold Quantum Particles Break Classical Symmetry

(EurekaAlert) Researchers from the Center for Quantum Dynamics at Heidelberg University have proven for the first time the theoretically predicted deviation from classical symmetry in laboratory experiments with ultracold lithium atoms.
the researchers studied the behaviour of an ultracold, superfluid gas of lithium atoms. When the gas is moved out of its equilibrium state, it starts to repeatedly expand and contract in a “breathing” motion. Unlike classical particles, these quantum particles can bind into pairs and, as a result, the superfluid becomes stiffer the more it is compressed. The group headed by primary authors Dr Puneet Murthy and Dr Nicolo Defenu – colleagues of Prof. Jochim and Dr Enss – observed this deviation from classical scale symmetry and thereby directly verified the quantum nature of this system.
The researchers report that this effect gives a better insight into the behaviour of systems with similar properties such as graphene or superconductors, which have no electrical resistance when they are cooled below a certain critical temperature.