Bose-Einstein condensates in 1D optical lattices: nonlinearity and Wannier-Stark spectra

TL;DR

This paper experimentally studies how nonlinearity affects Bloch oscillations, Landau-Zener tunneling, and resonant tunneling in a rubidium Bose-Einstein condensate within an optical lattice, revealing asymmetries and energy level interactions.

Contribution

It provides new experimental insights into nonlinear effects on tunneling phenomena and energy spectra in BECs in optical lattices.

Findings

Nonlinearity causes asymmetry in Landau-Zener tunneling.

Resonantly enhanced tunneling observed between Wannier-Stark levels.

Nonlinear modifications significantly impact Bloch oscillations.

Abstract

We present our experimental investigations on the subject of nonlinearity-modified Bloch-oscillations and of nonlinear Landau-Zener tunneling between two energy bands in a rubidium Bose Einstein condensate in an accelerated periodic potential. Nonlinearity introduces an asymmetry in Landau-Zener tunneling. We also present measurements of resonantly enhanced tunneling between the Wannier-Stark energy levels for Bose-Einstein condensates loaded into an optical lattice.