Title: Optically Spin-Stirred Cavity Polariton Condensates in a "Rotating Bucket" Experiment
Abstract: In this talk I will introduce recent experiments on optically stirred quantum fluids of light known as exciton-polariton condensates. We utilize spatial light modulators to superimpose two frequency-detuned optical vortex beam profiles which results in a net-beam profile of broken axial symemtry rotating at GHz rates about the optical axis of a planar semiconductor microcavity. Our beam nonresonantly invokes a chiral response in the photoexcited reservoir of excitons which undergo stimulated scattering into a out-of-equilibrium condensate whihc adopts the rotation direction of the beam. Our all-optical techniques permit non-invasive and in situ control over the vorticity of the polariton condensate with remarkable fidelity. We observe that clusters of co-rotating vortices in the polariton fluid can form in a similar spirit to archetypical "rotating bucket" experiments on superfluid Helium.
Extended our technique to spinor polaritons, we are able to modulate and control the condensate pseudospin at MHz rates while, interestingly, at GHz rates we locate a quantum fluidic analogue of the famous Nuclear Magnetic Resonance effect arising from the interplay between the strong interparticle condensate interactions and the rotation frequency of the beam. Our findings provide unique insight into dissipative scalar and vectorial quantum fluids under a time-modulated external drive.