Ultracold Lattice Gases with Periodically Modulated Interactions

TL;DR

This paper explores how periodic modulation of interactions in ultracold lattice gases can induce nonlinear hopping, leading to novel quantum phases and observable density profile features in experiments.

Contribution

It introduces a new mechanism of nonlinear hopping driven by periodically modulated interactions, revealing rich quantum phases in cold gases in optical lattices.

Findings

Discovery of pair superfluidity and defect-free Mott insulators with nonlinear hopping.

Identification of pure holon and doublon superfluids.

Predicted abrupt density drops at phase interfaces in trapped gases.

Abstract

We show that a time-dependent magnetic field inducing a periodically modulated scattering length may lead to interesting novel scenarios for cold gases in optical lattices, characterized by a nonlinear hopping depending on the number difference at neighboring sites. We discuss the rich physics introduced by this hopping, including pair superfluidity, exactly defect-free Mott-insulator states for finite hopping, and pure holon and doublon superfluids. We also address experimental detection, showing that the introduced nonlinear hopping may lead in harmonically trapped gases to abrupt drops in the density profile marking the interface between different superfluid regions.