Strain and pseudo-magnetic fields in optical lattices from density-assisted tunneling

TL;DR

This paper demonstrates how density-assisted tunneling in optical lattices can simulate strain effects in graphene, creating pseudo-magnetic fields and Landau levels in a cold atom system.

Contribution

It introduces a method to engineer strain-like gauge fields in optical lattices using density-assisted tunneling with a Bose-Einstein condensate.

Findings

Simulation of pseudo-magnetic fields in optical lattices.

Observation of relativistic Landau levels.

Valley Hall effect in a cold atom setup.

Abstract

Applying time-periodic modulations is routinely used to control and design synthetic matter in quantum-engineered settings. In lattice systems, this approach is explored to engineer band structures with non-trivial topological properties, but also to generate exotic interaction processes. A prime example is density-assisted tunneling, by which the hopping amplitude of a particle between neighboring sites explicitly depends on their respective occupations. Here, we show how density-assisted tunneling can be tailored in view of simulating the effects of strain in synthetic graphene-type systems. Specifically, we consider a mixture of two atomic species on a honeycomb optical lattice: one species forms a Bose-Einstein condensate in an anisotropic harmonic trap, whose inhomogeneous density profile induces an effective uniaxial strain for the second species through density-assisted tunneling processes. In direct analogy with strained graphene, the second species experiences a pseudo magnetic field, hence exhibiting relativistic Landau levels and the valley Hall effect. Our proposed scheme introduces a unique platform for the investigation of strain-induced gauge fields and their possible interplay with quantum fluctuations and collective excitations.