Trap anharmonicity and sloshing mode of a Fermi gas

TL;DR

This paper investigates how anharmonic trap potentials affect the sloshing mode of a degenerate Fermi gas, revealing frequency shifts and damping mechanisms through theoretical modeling aligned with experimental observations.

Contribution

It provides a detailed theoretical analysis of anharmonicity effects on sloshing modes in Fermi gases using the Boltzmann equation, including in-medium effects and mode coupling.

Findings

Frequency shifts match experimental data

Damping caused by mode coupling

Higher-order mode effects analyzed

Abstract

For a gas trapped in a harmonic potential, the sloshing (or Kohn) mode is undamped and its frequency coincides with the trap frequency, independently of the statistics, interaction and temperature of the gas. However, experimental trap potentials have usually Gaussian shape and anharmonicity effects appear as the temperature and, in the case of Fermions, the filling of the trap are increased. We study the sloshing mode of a degenerate Fermi gas in an anharmonic trap within the Boltzmann equation, including in-medium effects in both the transport and collision terms. The calculated frequency shifts and damping rates of the sloshing mode due to the trap anharmonicity are in satisfactory agreement with the available experimental data. We also discuss higher-order dipole, octupole, and bending modes and show that the damping of the sloshing mode is caused by its coupling to these modes.