Vortex stability and permanent flow in nonequilibrium polariton condensates

The following article appeared in Journal of Applied Physics 109.10 (2011): 102406 and may be found at http://scitation.aip.org/content/aip/journal/jap/109/10/10.1063/1.3576151We study the effects of imprinting a single-quantized vortex on the steady state of a microcavity exciton-polariton condensate generated via parametric scattering. Interestingly we observe two distinct regimes: In the first case, at low polariton densities, the effect of the pulsed probe, containing the vortex state, is to generate a gain response in the condensate lasting for tens of picoseconds during which no dissipation of the circulating currents is detected. In the second regime, at higher densities, the gain lasts much less and the circulation is imprinted directly into the steady state, which acquires permanent rotation for as long as the vortex remains within the condensate. We use two different ways of measuring the circulation of the condensate and demonstrate that in both cases, polariton condensation in the parametric scattering regime can sustain permanent supercurrentsThis work was partially supported by the Spanish MEC (MAT2008-01555 and QOIT-CSD2006-00019), the CAM (S2009/ESP-1503) and FP7 ITNs “Clermont4” (235114). D.S. acknowledges financial support from the Ramón y Cajal program. G.T. is grateful for the FPI scholarship from the Ministerio de Ciencia e Innovació