Collective excitations of a Bose-Einstein condensate in an anharmonic trap

TL;DR

This paper analyzes the collective excitations of a one-dimensional Bose-Einstein condensate in an anharmonic trap, revealing how anharmonicity affects excitation frequencies and nonlinear mode coupling.

Contribution

It introduces an analytical approach to study low-energy excitation modes in a BEC within a combined quadratic and quartic trap, highlighting anharmonic effects.

Findings

Frequency shift due to anharmonic distortion

Collapse and revival phenomena in collective excitations

Analytical expressions for excitation modes

Abstract

We investigate the collective excitations of a one-dimensional Bose-Einstein condensate (BEC) with repulsive interaction between atoms in a quadratic plus quartic trap. By using the variational approach, the coupled equations of motion for the center-of-mass coordinate of the condensate and its width are derived. Then, two low-energy excitation modes are obtained analytically. The frequency shift induced by the anharmonic distortion, and the collapse and revival of the collective excitations, which originate from the nonlinear coupling between the two modes, are discussed.