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Center for Nonlinear Studies |
Exciton-polaritons are quasiparticles that are formed when excitons in a quantum well are strongly coupled to light. Recently, exciton-polariton condensates have been produced, providing opportunities to study quantum many-body physics in a system that can be probed optically. The optical coupling also means quantum control techniques such as adiabatic rapid passage (ARP) can be used. I will discuss the use of ARP to prepare initial many-body states in these systems. One example realises a "quantum quench" experiment that is analogous to the Cooper problem in superconductivity. Mean-field theory predicts that the time evolution of the system leads to a non-equilibrium condensate with a time-oscillating amplitude. Calculating the fluctuation spectrum shows that this state is unstable to the formation of a spatially modulated phase. Many proposals for quantum light-matter experiments involve their use as model systems with strong interactions. Considering a simple model of interacting two-level systems, it is possible to identify some of the effects these interactions introduce when using ARP for state preparation.
Host: Avadh Saxena, 667-5227