Helene Perrin – Universite Sorbonne Paris Nord
Superfluid dynamics in a bubble
Quantum gases represent with a very convenient and widely tunable system for the study of superfluidity. In particular, they can be confined in a large variety of geometries (harmonic traps, optical lattices, box traps, lower dimensional traps…), enabling the study of superfluid dynamics with specific contraints. In my talk I will describe two recent experiments performed in the BEC group of Sorbonne Paris Nord University with a Bose quantum gas confined in a rotationally invariant shell trap, i.e. trapped at the surface of a “bubble”: the atoms can move freely in directions parallel to the surface and are strongly confined in the transverse direction. In the first experiment, the atoms initially at rest at the bottom of the shell – because of gravity – are set into fast rotation until the centrifugal force pushes them away from the bottom such that they form an annular cloud rotating at supersonic speeds. In the second experiment, we implement a way to compensate gravity on the shell. We evidence new effects that prevent the atoms to fill the entire shell, leading again to an annular density distribution but this time in equilibrium.
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