Interaction-controlled transport of an ultracold Fermi gas

TL;DR

This study investigates how interactions influence the transport dynamics of an ultracold Fermi gas in a 3D optical lattice, revealing controllable behavior through interaction tuning and evidence of pair formation.

Contribution

It demonstrates dynamic control of transport properties in an ultracold Fermi gas by tuning interactions, and provides insights into pair formation and low-temperature states.

Findings

Weakly damped oscillations in non-interacting gas become slow relaxation with strong attraction.

Interaction tuning allows dynamic control of transport behavior.

Measurement of doubly occupied sites indicates low temperature and pair formation.

Abstract

We explore the transport properties of an interacting Fermi gas in a three-dimensional optical lattice. The center of mass dynamics of the atoms after a sudden displacement of the trap minimum is monitored for different interaction strengths and lattice fillings. With increasingly strong attractive interactions the weakly damped oscillation, observed for the non-interacting case, turns into a slow relaxational drift. Tuning the interaction strength during the evolution allows us to dynamically control the transport behavior. Strong attraction between the atoms leads to the formation of local pairs with a reduced tunneling rate. The interpretation in terms of pair formation is supported by a measurement of the number of doubly occupied lattice sites. This quantity also allows us to determine the temperature of the non-interacting gas in the lattice to be as low as (27\pm2)% of the Fermi temperature.