Oscillations of Bose condensates in a one-dimensional optical superlattice

TL;DR

This paper studies the oscillation modes of Bose-Einstein condensates in a one-dimensional optical superlattice, revealing how mode dispersions depend on tunneling strengths and on-site interactions, providing a method to experimentally probe these parameters.

Contribution

It provides a detailed analysis of the mode spectrum in a 1D optical superlattice, highlighting the dependence on tunneling and interaction parameters, which was not previously characterized.

Findings

Four distinct oscillation modes are identified.

Mode dispersions depend on tunneling strengths $J_1$, $J_2$, and interaction $U$.

Observation of modes allows direct measurement of system parameters.

Abstract

Oscillations of atomic Bose-Einstein condensates in a 1D optical lattice with a two-point basis is investigated. In the low-frequency regime, four branches of modes are resolved, that correspond to the transverse in-phase and out-of-phase breathing modes, and the longitudinal acoustic and optical phonon modes of the condensates. Dispersions of these modes depend intimately on the values of two intersite Josephson tunneling strengths, $J_1$ and $J_2$, and the on-site repulsion $U$ between the atoms. Observation of these mode dispersions is thus a direct way to access them.