# Séminaire du LPTMS: Giulia De Rosi

## Collective oscillations of trapped atomic gases in low dimensions: a tool for the investigation of collisional processes

### Giulia De Rosi (Università di Trento, Italia)

Since 20 years, both theoretical and experimental investigation of collective oscillations has been carried out in trapped quantum gases. Fermionic and bosonic gases at different interaction, temperature, dimensions and geometrical configurations have been studied. We show a unified description of collective modes for all above atomic gases. All collective frequencies have been calculated by solving a single equation for the flow velocity derived starting from the hydrodynamic equations. Moreover, by using the sum- rule approach, we predict a different excitation signal at high temperature for the dipole compression mode in the hydrodynamic (single frequency) and collisionless (beating of 2 frequencies) regime for a one dimension (1D) harmonically trapped Bose gas. This theoretical prediction opens promising perspectives for the experimental investigation of collisional effects in 1D.

References:

- G. De Rosi and S. Stringari,
*Collective oscillations of a trapped quantum gas in low dimensions*, Phys. Rev. A 92 , 053617 (2015). - G. De Rosi and S. Stringari,
*Hydrodynamic VS collisionless dynamics of a 1D harmonically trapped Bose gas*, to appear in Phys. Rev. A, preprint arXiv:1608.08417

**Date/Time : ** 15/11/2016 - *11:00 - 12:00*

**Location : ** LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay

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