| Network Teams: |
Department of Physics, Theory of Condensed Matter Group, University of Cambridge
The Cambridge team comprises a group of theoreticians with a wide experience of condensed matter theory. Our experience ranges from the study of simple models for quantum dots coupled to photons, through detailed first-principles calculations of the electronic and optical properties of quantum wells, to theories of localisation and decoherence in disordered metals and superconductors. Our role will be to provide theoretical support and guidance for the experimental teams in the Network. This support will take three forms:
- Using simple models to elucidate the fundamental physics of QWs and QDs in photonic structures.
- Developing, in close collaboration with the experimental groups, detailed models of specific experiments.
- Using our models as tools to characterise the experiments.
Recently, the investigation of novel collective behaviour has formed a central theme in our work. We were the first to explore theoretically, using an idealised model, the possibility of photon-mediated Bose condensation in an ensemble of quantum dots embedded in an optical cavity. We have shown that such a Bose condensate is related to a laser, but occurs when the coupling between the dots and the photons is large compared with the strength of the decoherence, while lasing occurs in the opposite regime. The models we have used so far are deliberately idealised, because we have been interested in establishing the fundamental concepts, and the qualitative experimental criteria for the observation of collective ground states. With these experiences developing theories in models of quantum dots, we are well-placed to develop theoretical descriptions of these and other collective phenomena in more refined models. The physical systems for which these ideas may be appropriate include semiconductor MC work at Grenoble and high-Q spherical MC experiments in Dortmund.
Another major theme within our group has been the physics of disordered metals and superconductors, particularly localisation and decoherence. There is now a well-developed understanding of electron transport in mesoscopic systems, and we believe that the theoretical approaches used there can be generalised to understand photon transport in weakly disordered optical systems. The combination of experience, of both semiconductor optics and disordered systems, in our group will be fruitful for work on the optics of disordered semiconductors; work that will directly address experimental issues in quasi-2D semiconductor structures.
In collaboration with the Cardiff group, we have already been involved in several pieces of work, especially modelling relaxation kinetics of excitons in 2D structures and in interpreting experiments (from Dortmund) that give the first evidence for coherently coupled polariton-acoustic phonon modes ("phonoritons").
As a theoretical group, we complement the experimental groups in the Network, to whom links will be vital, because the interplay between experiment and theory is essential to progress in this field. The theoretical expertise in the group at Cardiff is complementary to ours, and we have already very close collaborations there.
Scientific staff involved:
| Name | Interests |
| Peter Littlewood | Decoherence, laser physics |
| Paul Eastham | Bose-Einstein condensation, Rayleigh scattering |
| Ben Simons | Superfluids with disorder, quantum chaos |
| Marzena Szymanska | Bose-Einstein condensation |
Significant recent publications:
- Eastham, P.R. & Littlewood, P.B., Bose condensation in a model microcavity, 2000, Solid State Comm. 116, 357.
- Lamacraft, A. & Simons, B.D., Tail states in a superconductor with magnetic impurities, 2000, Phys. Rev. Lett. 85, 4783.
