Density-dependent synthetic magnetism for ultracold atoms in optical lattices

TL;DR

This paper explores how density-dependent synthetic magnetism in ultracold atoms in optical lattices induces complex phase transitions and density modulations, revealing rich physics in ladder and square lattice configurations.

Contribution

It introduces a novel approach to generate density-dependent synthetic magnetic fields and analyzes their effects on superfluid and density-wave phases in optical lattices.

Findings

Density-driven Meissner- to vortex-superfluid transition in two-leg ladders.

Transition between non-chiral and chiral superfluids in square lattices.

Experimental signatures in doublon and hole expansion dynamics.

Abstract

Raman-assisted hopping can allow for the creation of density-dependent synthetic magnetism for cold neutral gases in optical lattices. We show that the density-dependent fields lead to a non-trivial interplay between density modulations and chirality. This interplay results in a rich physics for atoms in two-leg ladders, characterized by a density-driven Meissner- to vortex-superfluid transition, and a non-trivial dependence of the density imbalance between the legs. Density-dependent fields also lead to intriguing physics in square lattices. In particular, it leads to a density-driven transition between a non-chiral and a chiral superfluid, both characterized by non-trivial charge density-wave amplitude. We finally show how the physics due to the density-dependent fields may be easily probed in experiments by monitoring the expansion of doublons and holes in a Mott insulator, which presents a remarkable dependence on quantum fluctuations.