# Collective oscillations in ultracold atomic gases

## TL;DR

This paper explores the fundamental oscillations and wave phenomena in ultracold atomic gases, revealing hybrid plasma-acoustic modes, resonance behaviors, and damping processes through fluid and kinetic models.

## Contribution

It introduces the concept of hybrid plasma-acoustic modes in ultracold gases and analyzes their resonances and damping mechanisms using combined fluid and kinetic descriptions.

## Key findings

- Identification of hybrid plasma-acoustic modes
- Analysis of Tonks-Dattner resonances in spherical clouds
- Discussion of Landau damping and nonlinear coupling

## Abstract

Using both fluid and kinetic descriptions, where repulsive forces between near by atoms are included, we discuss the basic oscillations and waves of a cloud of ultra-cold atoms confined in a magneto-optical trap. The existence of a hybrid mode, with properties similar to both plasma and acoustic waves is described in detail. Tonks-Dattner resonances for confined hybrid modes in a spherical cloud are discussed and the prediction of a nonlinear coupling between the dipole resonanc and the hybrid modes is considered. Landau damping processes and quasi-linear diffusion in velocity space are also discussed.