Observations of $\lambda/4$ structure in a low-loss radiofrequency-dressed optical lattice

TL;DR

This paper demonstrates the creation of a stable, radiofrequency-dressed optical lattice for Bose-Einstein condensates, revealing significant differences in momentum distributions and achieving longer lifetimes than previous studies.

Contribution

It introduces a method to produce more stable, deeper rf-dressed optical lattices with increased coupling, enabling new experiments in quantum simulation.

Findings

Observed stable dressed lattices with lifetimes exceeding tens of milliseconds.

Found significant differences in BEC momentum distributions compared to bare lattices.

Achieved longer lifetimes by increasing the rf coupling strength, reducing Landau-Zener tunnelling losses.

Abstract

We load a Bose-Einstein condensate into a one-dimensional (1D) optical lattice altered through the use of radiofrequency (rf) dressing. The rf resonantly couples the three levels of the $^{87}$Rb $F=1$ manifold and combines with a spin-dependent "bare" optical lattice to result in adiabatic potentials of variable shape, depth, and spatial frequency content. We choose dressing parameters such that the altered lattice is stable over lifetimes exceeding tens of ms at higher depths than in previous work. We observe significant differences between the BEC momentum distributions of the dressed lattice as compared to the bare lattice, and find general agreement with a 1D band structure calculation informed by the dressing parameters. Previous work using such lattices was limited by very shallow dressed lattices and strong Landau-Zener tunnelling loss between adiabatic potentials, equivalent to failure of the adiabatic criterion. In this work we operate with significantly stronger rf coupling (increasing the avoided-crossing gap between adiabatic potentials), observing dressed lifetimes of interest for optical lattice-based analogue solid-state physics.