Superfluid backjet of a two dimensional polariton condensate

What is it about?

This works shows the spectacular phenomenology which is observed when a resonant photonic drop impacts the polariton vacuum field inside a microcavity. The light pulse is istantaneously converted into a two-dimensional polariton fluid, an hybrid gas of coupled photonic and excitonic oscillations, which is left free to evolve and studied by means of ultrafast imaging.

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Why is it important?

The unique feature consists in the dynamical accumulation of the polariton quasi-particles in a central bright peak which is much thinner and locally more intense than the initial gaussian spot. This is striking because of the polariton effective mass (positive curvature of the dispersion around k=0) and repulsive interactions (positive nonlinearities), highlighting a non-standard effect at play here. The response time, enhancement and localization factors are tuned continuosly with the initial density (ie. exciting powers). The experiments highlight a variegated phenomenology consisting also of sub-picosecond Rabi oscillations, circular shock waves and ring dark solitons. They show that exotic phenomena are still to be comprehended in the ultrafast dynamics of polariton fluids at high density regimes.