Interaction-induced conducting-nonconducting transition of ultra-cold atoms in 1D optical lattices

TL;DR

This paper investigates how spatially inhomogeneous interactions in 1D optical lattices can induce a transition from conducting to nonconducting states in ultra-cold fermionic atoms, revealing negative differential conductance phenomena.

Contribution

It demonstrates the emergence of a conducting-to-nonconducting transition driven by interaction imbalance, using advanced simulation methods including mean-field, higher-order approximations, and time-dependent DMRG.

Findings

Robust atomic current for weak interactions similar to electronic systems.

Existence of a conducting-to-nonconducting transition at a threshold interaction imbalance.

Observation of negative differential conductivity preceding the transition.

Abstract

The study of time-dependent, many-body transport phenomena is increasingly within reach of ultra-cold atom experiments. We show that the introduction of spatially inhomogeneous interactions, e.g., generated by optically-controlled collisions, induce negative differential conductance in the transport of atoms in 1D optical lattices. Specifically, we simulate the dynamics of interacting fermionic atoms via a micro-canonical transport formalism within both mean-field and a higher-order approximation, as well as with time-dependent DMRG. For weakly repulsive interactions, a quasi steady-state atomic current develops that is similar to the situation occurring for electronic systems subject to an external voltage bias. At the mean-field level, we find that this atomic current is robust against the details of how the interaction is switched on. Further, a conducting-to-nonconducting transition exists when the interaction imbalance exceeds some threshold from both our approximate and time-dependent DMRG simulations. This transition is preceded by the atomic equivalent of negative differential conductivity observed in transport across solid-state structures.