Damped Bloch Oscillations of Bose-Einstein Condensates in Disordered Potential Gradients

TL;DR

This study explores how disorder-induced inhomogeneities cause damping of Bloch oscillations in Bose-Einstein condensates within optical lattices, combining experimental observations with theoretical simulations to understand the underlying mechanisms.

Contribution

It provides a quantitative analysis of damping mechanisms due to disorder in optical lattices, linking inhomogeneous forces to quasimomentum broadening and oscillation damping.

Findings

Disorder causes broadening of quasimomentum spectrum.

Inhomogeneous forces lead to damping of oscillations.

Simulations match experimental damping rates.

Abstract

We investigate both experimentally and theoretically disorder induced damping of Bloch oscillations of Bose-Einstein condensates in optical lattices. The spatially inhomogeneous force responsible for the damping is realised by a combination of a disordered optical and a magnetic gradient potential. We show that the inhomogeneity of this force results in a broadening of the quasimomentum spectrum, which in turn causes damping of the centre-of-mass oscillation. We quantitatively compare the obtained damping rates to the simulations using the Gross-Pitaevskii equation. Our results are relevant for high precision experiments on very small forces, which require the observation of a large number of oscillation cycles.