Cavity polaritons are particles which are formed from photons confined to a cavity coupled to electronic excitations such as semiconductor excitons. Since the observation of cavity polaritons in 1992, there has been considerable interest in the quantum statistical behaviour of cavity polaritons. This thesis is a theoretical study of one of the most spectacular quantum statistical behaviours, Bose condensation, for cavity polaritons. In this thesis, we investigate Bose condensation of cavity polaritons in a generic model of photons interacting with electronic excitations. The model we consider is a generalisation of the Dicke model, familiar from quantum optics. It consists of a single bosonic oscillator, describing the electromagnetic field in a cavity, interacting with a large number of two-state oscillators with a distribution of energies. These oscillators could represent, for example, excitons bound to traps in a disordered semiconductor. Bose condensation is a phenomenon associated with conserved particles in thermal equilibrium. Thus to investigate Bose condensed polaritons we study the thermodynamics of the model at a fixed number of polaritons. We do this using two techniques: a variational approach, and a more powerful path-integral technique. The latter allows us to give an essentially exact description of both the thermodynamics and the excitations of the model.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:598736 |
| Date | January 2001 |
| Creators | Eastham, P. R. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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