Damped Bloch oscillations of Bose–Einstein condensates in disordered potential gradients

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.

Dissipative transport of a Bose-Einstein condensate

“…Consequently, v 0 is always greater than the local speed of sound at the edge of the condensate, and excitations are always present. Previous experimental [34,36,43] and numerical [44] studies of the damping of collective modes and the damping of Bloch oscillations in a disordered lattice potential [45,46] have found qualitatively similar results. Figure 4 shows in situ polarization phase-contrast images [47] of the BEC at various times in the oscillation shown in Fig.…”

Bloch oscillations of an exciton-polariton Bose-Einstein condensate

“…This interplay has serious consequences for the phase diagram of the system, 34,35 and most importantly, the disorder induces extra dephasing, which is revealed by a damping of the matter wave's BOs. 36,37 Currently, several works have already been devoted to the behavior of polariton condensates in periodic lattices, [38][39][40][41][42] and this topic has started to attract a lot of attention. In this paper we theoretically describe BOs of polaritons in a patterned one-dimensional microwire.…”

Experimental studies of Bose–Einstein condensates in disorder

“…In contrast to the disorder due to material defects in typical solid state systems, such optical disorder is of great advantage because the disordered potential is easily tunable and can be precisely characterized. Three types of optical disorder have been used so far: laser speckle [16,18,21], image of a disordered substrate [19,24] and quasi-random (incommensurate) optical lattices [20,26]. The different types of disorder could lead to different physics of disordered BECs, as has been discussed in the case of disorder-induced localization [12,37].…”

“…Studying disordered BECs may also provide valuable insights to understand the behaviors of nonlinear systems in the presence of randomness. Since 2005, there have been a flurry of experimental activities [16][17][18][19][20][21][22][23][24][25][26][27] to study BECs in disordered potentials. The physics investigated have included disorder induced inhibition of transport [16][17][18][19]21], effects of disorder on collective modes [16,21,24], Bose glass [20], granular BEC and phase coherence [21], density modulations [21,22], disordered Bose-Hubbard model [23], Anderson localization [25,26] and solitons in disorder [27].…”