This thesis presents experiments performed to investigate the non-equilibrium dynamics of ultracold bosons. In depth understanding of the behaviour of quantum systems when taken out of equilibrium is of particular interest, especially for the production of quantum computers where thermal effects cause undesirable behaviours. We present our experiments on the thermalization of a87Rb Bose-Einstein condensate taken out of equilibrium by a partial Bragg pulse. We measure the rate of thermalization of the system and measure the temperature of the thermalized state, and compare to numerical simulations. We observe the formation of grey solitons in the thermalized state consistent with the Kibble-Zurek mechanism. We also present experiments on artificial gauge potentials with Bose-Einstein condensates. We benchmark the experiments with a uniform synthetic potential and extend to spin-orbit coupled systems. We take the spin-orbit coupled BEC out of equilibrium through the application of a synthetic electric field and measure the thermalization process of the system. We measure the rate at which the system reaches equilibrium as a function of the final Raman coupling strength, and measure the temperature of the thermalized states. We observe the system thermalize into a spin-orbit coupled state with a the final temperature decreasing with increasing Raman coupling.

Bose-Einstein condensation of excitons is a unique effect in which the electronic states of a solid can self-organize to acquire quantum phase coherence. The phenomenon is closely linked to Bose-Einstein condensation in other systems such as liquid helium and laser-cooled atomic gases. This is the first book to provide a comprehensive survey of this field, covering theoretical aspects as well as recent experimental work. After setting out the relevant basic physics of excitons, the authors discuss exciton-phonon interactions as well as the behaviour of biexcitons. They cover exciton phase transitions and give particular attention to nonlinear optical effects including the optical Stark effect and chaos in excitonic systems. The thermodynamics of equilibrium, quasi-equilibrium, and nonequilibrium systems are examined in detail. The authors interweave theoretical and experimental results throughout the book, and it will be of great interest to graduate students and researchers in semiconductor and superconductor physics, quantum optics, and atomic physics.

Following an explosion of research on Bose–Einstein condensation (BEC) ignited by demonstration of the effect by 2001 Nobel prize winners Cornell, Wieman and Ketterle, this book surveys the field of BEC studies. Written by experts in the field, it focuses on Bose–Einstein condensation as a universal phenomenon, covering topics such as cold atoms, magnetic and optical condensates in solids, liquid helium and field theory. Summarising general theoretical concepts and the research to date - including novel experimental realisations in previously inaccessible systems and their theoretical interpretation - it is an excellent resource for researchers and students in theoretical and experimental physics who wish to learn of the general themes of BEC in different subfields.