Dynamics and decay of solitary excitations in superfluid Fermi gases
25 mei 2020
ONLINE - -- - -- --
Organisatie / co-organisatie:
Wout Van Alphen
ONLINE Doctoraatsverdediging Wout Van Alphen - Faculteit Wetenschappen, Departement Fysica
Ultracold quantum gases consist of a collection of magnetically or optically trapped atoms cooled down to nanokelvin temperatures. At these ultralow temperatures, the laws of quantum mechanics, which are usually confined to the microscopic world of atoms and particles, now become apparent on the macroscopic scale of the entire cloud. This leads to remarkable behavior, such as the occurrence of flow without friction or “superfluidity”. In addition, these ultracold atomic gases possess a very high experimental tunability, thus making them the ideal systems for the study of quantum phenomena.
Non-linear excitations like dark solitons and quantized vortices play an important role in the dynamics of superfluid systems. A dark soliton is a solitary dip in the density of the fluid which does not change shape while propagating at a constant velocity, while a quantized vortex is the quantum equivalent of a whirlpool in classical hydrodynamics. Although several aspects of these solitary excitations have already been thoroughly examined in bosonic superfluids, much remains to be learned about their properties and dynamics in fermionic superfluids, which possess a more complex but also much richer physics than their bosonic counterparts. The aim of this thesis is to provide a detailed theoretical analysis of solitary excitations in fermionic quantum gases, through the use of a finite-temperature, low-energy effective field theory that was developed specifically for these systems. Our studies on the dynamics, stability and interactions of solitons and vortices throughout the various unique regimes of the superfluid Fermi gas demonstrate the emergence of new and interesting features that are clearly different from the established behavior of solitary excitations in bosonic quantum gases.