Tilman Esslinger at the Department of Physics of ETH Zurich now reports on the controlled reversal of such a current by changing the interaction strength among the constituents of a quantum simulator made of extremely cold atoms trapped in shaped laser fields.
The experiment, conducted by doctoral researcher Samuel Häusler and co-workers in the Esslinger group, starts with a cloud of fermionic Lithium atoms that are cooled to temperatures low enough that quantum effects determine the behaviour of the ensemble.
Thanks to the exquisite control over the system, the researchers were able to measure the transient behaviours for different interaction strengths and atomic densities inside the channel and compared them to a simple model.
With a non-interacting gas, it is possible to compute the dominating trend between the two competing effects once the precise shape of the atom cloud is known and taken into account.
In this regime, the quantum simulation device of the ETH researchers showed that for high-enough mean temperature and low atom density in the channel, the current also flows from the hot to the cold reservoir.
While this enhancement cannot be directly translated into material science, this excellent cooling capability could already be used to reach lower temperatures for atomic gases, which in turn might enable a broad range of novel fundamental experiments in quantum science.