Nonlinear dynamics in a synthetic momentum state lattice

TL;DR

This paper investigates how atomic interactions in a synthetic momentum state lattice lead to nonlinear effects, such as self-trapping and Josephson dynamics, enriching the understanding of many-body phenomena in synthetic dimensions.

Contribution

It demonstrates the impact of strong interactions on dynamics in a synthetic momentum lattice, revealing nonlinear phenomena absent in single-particle models.

Findings

Atomic interactions cause large, qualitative changes in synthetic dimension dynamics.

Observation of macroscopic self-trapping and phase-driven Josephson effects.

Nonlinear band structure effects emerge from interactions.

Abstract

The scope of analog simulation in atomic, molecular, and optical systems has expanded greatly over the past decades. Recently, the idea of synthetic dimensions -- in which transport occurs in a space spanned by internal or motional states coupled by field-driven transitions -- has played a key role in this expansion. While approaches based on synthetic dimensions have led to rapid advances in single-particle Hamiltonian engineering, strong interaction effects have been conspicuously absent from most synthetic dimensions platforms. Here, in a lattice of coupled atomic momentum states, we show that atomic interactions result in large and qualitative changes to dynamics in the synthetic dimension. We explore how the interplay of nonlinear interactions and coherent tunneling enriches the dynamics of a one-band tight-binding model, giving rise to macroscopic self-trapping and phase-driven Josephson dynamics with a nonsinusoidal current-phase relationship, which can be viewed as stemming from a nonlinear band structure arising from interactions.