Tuning the mobility of a driven Bose-Einstein condensate via diabatic Floquet bands

TL;DR

This paper demonstrates how strong periodic driving of an optical lattice can control the mobility of a Bose-Einstein condensate, enabling ballistic motion either along or against an applied force, through the formation of diabatic Floquet bands.

Contribution

It provides experimental evidence and theoretical analysis of diabatic Floquet bands controlling non-equilibrium transport in driven Bose-Einstein condensates.

Findings

Strong ac-driving tailors atomic mobility

Ballistic motion along or against force direction

Existence of diabatic Floquet bands in spectra

Abstract

We study the response of ultracold atoms to a weak force in the presence of a temporally strongly modulated optical lattice potential. It is experimentally demonstrated that the strong ac-driving allows for a tailoring of the mobility of a dilute atomic Bose-Einstein condensate with the atoms moving ballistically either along or against the direction of the applied force. Our results are in agreement with a theoretical analysis of the Floquet spectrum of a model system, thus revealing the existence of diabatic Floquet bands in the atom's band spectra and highlighting their role in the non-equilibrium transport of the atoms.