Bloch Oscillations and Mean-Field Effects of Bose-Einstein Condensates in 1D Optical Lattices

Abstract

We have loaded Bose-Einstein condensates into one-dimensional, off-resonant optical lattices and accelerated them by chirping the frequency difference between the two lattice beams. For small values of the lattice well depth, Bloch oscillations were observed. Reducing the potential depth further, Landau-Zener tunneling out of the lowest lattice band, leading to a breakdown of the oscillations, was also studied and used as a probe for the effective potential resulting from mean-field interactions as predicted by Choi and Niu [Phys. Rev. Lett. 82, 2022 (1999)]. The effective potential was measured for various condensate densities and trap geometries, yielding good qualitative agreement with theoretical calculations.

Self-trapping of Bose-Einstein condensates in optical lattices

“…In such a bosonic system, people have observed well-known and long predicted phenomena, such as Bloch oscillations [1] and the quantum phase transition between superfluid and Mottinsulator [2]. More importantly, there are new phenomena that have been either observed or predicted in this system, for example, nonlinear Landau-Zener tunneling between Bloch bands [3,4] and the strongly inhibited transport of one dimensional BEC in an optical lattice [5].…”

Dark soliton dynamics in spatially inhomogeneous media: Application to Bose–Einstein condensates

“…Apart from the above, theoretical and experimental BEC studies have been performed in the case of a periodic external potential, the so-called optical lattice (OL) trap created by interference patterns from multiple laser beams [16][17][18][19][20][21]. The experimental control over the OL has led to the realization of numerous interesting phenomena including Bloch oscillations [18,22], Landau-Zener tunneling [16] (in the additional presence of a linear external potential), and classical [23] and quantum [21] superfluidinsulator transitions.…”

“…The experimental control over the OL has led to the realization of numerous interesting phenomena including Bloch oscillations [18,22], Landau-Zener tunneling [16] (in the additional presence of a linear external potential), and classical [23] and quantum [21] superfluidinsulator transitions. With respect to the above, the dissipative dynamics of the DSs (including detailed quantitative measurements of the sound emitted by the soliton) in a quasi one-dimensional (1D) BEC confined through a harmonic trap and an OL, as well as the structure and the mobility properties of DSs in single and double-periodic OLs have recently been considered in [24,25], respectively.…”

Quantum kinetic theory of a Bose-Einstein gas confined in a lattice

“…In particular, by varying the depth of the optical lattice, the superfluid-insulator phase transition can be induced. For weakly-confining optical lattices, the system has macroscopic quantum coherence, and interesting matter wave interference phenomena induced by the periodicity of the lattice have been demonstrated in experiments [3,4,5,6]. For tightly-confining lattices, the matter-wave coherence is lost, and the system undergoes a transition to the Mott-insulator phase [7].…”