Abstract: The physics of many-body systems strongly depends on their dimensionality. With the realization of quantum wells, for example, it has been possible to produce two-dimensional (2-D) gases of electrons, which exhibit properties that differ dramatically from the standard three-dimensional case. During the last decade, a novel environment has been developed for the study of quantum physics in low dimension. It consists of cold atomic gases confined in tailor-made light traps, forming a thin layer of material particles.
In this talk, I will present some key aspects of these 2-D gases, such as quasi-long-range coherence and superfluidity. I will also discuss out-of-equilibrium features, such as the nucleation of random currents, and explain the crucial role of topology for understanding the properties of these quantum 2-D systems.