Formation of spontaneous density-wave patterns in DC driven lattices

TL;DR

This paper investigates how strong DC fields induce spontaneous density-wave patterns in ultracold bosonic lattice systems, revealing out-of-equilibrium phenomena and domain formation through experimental and theoretical analysis.

Contribution

It demonstrates the emergence of density wave patterns in a tilted Hubbard model using advanced imaging, expanding understanding of out-of-equilibrium dynamics in lattice systems.

Findings

Density wave patterns spontaneously form under strong DC fields.

Short-time dynamics are driven by resonant pair tunneling.

Novel imaging technique resolves domain structures in 3D.

Abstract

Driving a many-body system out of equilibrium induces phenomena such as the emergence and decay of transient states, which can manifest itself as pattern and domain formation. The understanding of these phenomena expands the scope of established thermodynamics into the out-of-equilibrium domain. Here, we experimentally and theoretically study the out-of-equilibrium dynamics of a bosonic lattice model subjected to a strong DC field, realized as ultracold atoms in a strongly tilted triangular optical lattice. We observe the emergence of pronounced density wave patterns -- which spontaneously break the underlying lattice symmetry -- using a novel single-shot imaging technique with two-dimensional single-site resolution in three-dimensional systems, which also resolves the domain structure. Our study suggests that the short-time dynamics arises from resonant pair tunneling processes within an effective description of the tilted Hubbard model. More broadly, we establish the far out-of-equilibrium regime of lattice models subjected to a strong DC field, as an exemplary and paradigmatic scenario for transient pattern formation.