Intrinsic Photoconductivity of Ultracold Fermions in Optical Lattices

TL;DR

This paper reports the experimental observation of persistent oscillations and revivals in an ultracold fermionic gas in an optical lattice, revealing complex photoconductivity phenomena analogous to electronic systems.

Contribution

It demonstrates the first experimental realization of an analog to persistent photocurrent in ultracold atoms, with a detailed theoretical explanation using a nonlinear pendulum model.

Findings

Long-lived oscillations in excited band particles

Collapse and revival dynamics in holes in the lowest band

Mapping of system dynamics to a nonlinear pendulum model

Abstract

We report on the experimental observation of an analog to a persistent alternating photocurrent in an ultracold gas of fermionic atoms in an optical lattice. The dynamics is induced and sustained by an external harmonic confinement. While particles in the excited band exhibit long-lived oscillations with a momentum dependent frequency a strikingly different behavior is observed for holes in the lowest band. An initial fast collapse is followed by subsequent periodic revivals. Both observations are fully explained by mapping the system onto a nonlinear pendulum.