The dynamics of condensate shells: collective modes and expansion

TL;DR

This paper investigates the unique collective excitations and expansion dynamics of three-dimensional shell-shaped Bose-Einstein condensates, revealing distinct breathing modes and self-interference phenomena through analytical and numerical methods.

Contribution

It introduces a detailed analysis of shell-shaped condensates' collective modes and expansion behavior, highlighting differences from traditional spherical condensates.

Findings

Identified two distinct breathing modes in shell-shaped condensates.

Observed self-interference fringes during expansion after trap release.

Estimated key dynamical parameters such as time scales and energy release.

Abstract

We explore the physics of three-dimensional shell-shaped condensates, relevant to cold atoms in "bubble traps" and to Mott insulator-superfluid systems in optical lattices. We study the ground state of the condensate wavefunction, spherically-symmetric collective modes, and expansion properties of such a shell using a combination of analytical and numerical techniques. We find two breathing-type modes with frequencies that are distinct from that of the filled spherical condensate. Upon trap release and subsequent expansion, we find that the system displays self-interference fringes. We estimate characteristic time scales, degree of mass accumulation, three-body loss, and kinetic energy release during expansion for a typical system of Rb87.