Optomechanical self-structuring in a Bose-Einstein ondensate

Self-organized patterns and structures which arise due to the simultaneous presence of optical nonlinearity and diffraction have been predicted and observed in a variety of media, including hot atomic vapours, for a number of years [1,2]. In cold and ultracold atomic gases the presence of optical dipole forces leads to density self-organization and removes the requirement for an intrinsic optical nonlinearity involving e.g. electronic or Zeeman states. We present results which show the existence of a transverse optomechanical instability in a quantum degenerate Bose-Einstein Condensate (BEC), which is expected to lead to a supersolid state breaking spontaneously two continuous symmetries during nonlinear evolution.