Collective Oscillations in ultracold trapped gases
An ultracold gas is considered as the coldest matter in the Universe. Thanks to its very low temperature, the quantum effects become very evident, by making the distinction between bosons and fermions more and more important. As a consequence of the quantum nature, many completely new and amazing physical properties appear which are not present in normal matter. Among them, I will focus on a macroscopic phenomenon of this kind of gases: the collective oscillations whose importance lies in considering them as an useful test to probe the superfluidity (absence of the viscosity) present in an ultracold gas. I have studied collective oscillations in the theoretical framework of the Hydrodynamic Theory and I will show the power of this very general approach in the study of ultracold gases for both quantum statistics, all dimensions and different geometrical regimes.