The high degree of control that exists in experiments with cold atoms, and Bose-Einstein condensates, in particular, allows us to design systems with chosen geometries. These provide us with simple model systems that are well understood from first principles microscopically, and with parameters controlled by external fields, as tools to explore new frontiers in the context of non-equilibrium dynamics. These possibilities can be used for a wide variety of applications, ranging from quantum simulations to quantum metrology. In this thesis, we investigate designing the confinement of tightly trapped impurities in a BEC reservoir to study their dissipative dynamics, and to study non-equilibrium dynamics of BECs confined in a tilted ring trap (both with ultracold atoms and polaritons).In the first part we explore tightly confined impurities, immersed in a weakly trapped BEC and initially excited in the strongly confined direction, to study cooling of the impurities to low-temperature states under realistic experimental conditions. This scheme, combined with dissipative state engineering, sets the basis for adaption of laser cooling techniques for the production of low-entropy states in quantum simulators. We can also use this system to access non-Markovian dynamics by changing the ratios of relevant timescales using control over the trapping of the impurities and the reservoir.In the second part we study the dynamics of a BEC confined in a 1D tilted ring trap, both with ultracold atoms and long-lifetime polaritons. We study the collective oscillations of a BEC in a tilted ring trap to characterise the effects generated by the interplay between non-linearities due to anharmonicity and non-linearities due to interactions. In the case of polaritons, we make comparison with experimentally observed features, and gain an understanding of the thermalisation process in such systems.
|Date of Award||22 Jun 2020|
- University Of Strathclyde
|Sponsors||EPSRC (Engineering and Physical Sciences Research Council)|
|Supervisor||Andrew Daley (Supervisor) & Gian-Luca Oppo (Supervisor)|