Inducing Transport in a Dissipation-Free Lattice with Super Bloch Oscillations

TL;DR

This paper demonstrates that periodic modulation near the Bloch frequency induces giant, transport-enabled super Bloch oscillations in a Bose-Einstein condensate, significantly enhancing coherence and suppressing instabilities in a dissipation-free lattice.

Contribution

It introduces super Bloch oscillations as a novel method to induce linear transport and control coherence in a quantum lattice system with interactions.

Findings

Giant center-of-mass oscillations across hundreds of lattice sites.

Super Bloch oscillations suppress dynamical instabilities.

Phase-coherence time increased by over a hundred times.

Abstract

Particles in a perfect lattice potential perform Bloch oscillations when subject to a constant force, leading to localization and preventing conductivity. For a weakly-interacting Bose-Einstein condensate (BEC) of Cs atoms, we observe giant center-of-mass oscillations in position space with a displacement across hundreds of lattice sites when we add a periodic modulation to the force near the Bloch frequency. We study the dependence of these "super" Bloch oscillations on lattice depth, modulation amplitude, and modulation frequency and show that they provide a means to induce linear transport in a dissipation-free lattice. Surprisingly, we find that, for an interacting quantum system, super Bloch oscillations strongly suppress the appearance of dynamical instabilities and, for our parameters, increase the phase-coherence time by more than a factor of hundred.