THE POLARITON BACKJET
( youtube link , cnr_press_rel )
Among the fascinating properties of polariton light fluids are the presence of both very fast response times united with strong nonlinear mutual interactions. These features along with the absence of dissipations due to conventional friction may give rise to the Bose Einstein condensation of the fluid, where all the bosonic particles acquire a common time and space frequency. Here we assist to another exotic penomenon, the spectacular dynamical accumulation of the particles in a central spot quite denser and much times thinner than the originally created drop of polaritons. If comparing the local 2D density of the polariton gas to the height of a water column ... this looks astonishingly similar to the backjet of a water drop hitting the liquid surface, yet being different... sharply micrometric... ultrafast... and an essential nonlinear effect.
Real-space collapse of a polariton condensate, Nature Commun. 6, 8993 (2015)