B\'enard-von K\'arm\'an vortex street in an exciton-polariton superfluid
  The dynamics of an exciton--polariton superfluid resonantly injected into a semiconductor microcavity are investigated numerically. The results reveal that a B\'enard--von K\'arm\'an vortex street is generated in the wake behind an obstacle potential, in addition to the generation of quantized vortex dipoles and dark solitons. The vortex street is shown to be robust against a disorder potential in a sample and it can be observed even in time-integrated measurements. 
Hiroki Saito, Tomohiko Aioi, Tsuyoshi Kadokura
cond-mat.mes-hall cond-mat.quant-gas