"Quantum and classical correlations in a cold dipolar exciton fluid":
Dipolar fluids are very important and abundant in nature, and yet their complex collective microscopic ordering and correlations are still not well understood. In particular cold two-dimensional dipolar fluids are predicted to display a very rich phase diagram in both the classical and quantum regimes, far beyond weakly interacting quantum gases. The observation and understanding of the states of quantum degenerate dipolar fluids are currently a major topic in modern atomic, molecular, and condense matter research.
In this talk I will introduce a system of dipolar excitons in semiconducting bilayers, which is a realization of a true 2D dipolar fluid. I will show experimental results unveiling complex particle correlation regimes of a cold dipolar exciton fluid. One surprise is the observation of a sharp darkening of the fluid emission below a critical temperature. I will discuss the possible mechanisms behind these experimental observations and their relation to the theoretically predicted quantum correlated phase and to a macroscopic spin ordering (condensation).
[1] Yehiel Shilo, et.al. "Particle correlations and evidence for dark state condensation in a cold dipolar exciton fluid" Nat Commun, 4, August 2013.