Dissipationless Flow and Sharp Threshold of a Polariton Condensate with Long Lifetime

We report new results of Bose-Einstein condensation of polaritons in specially designed microcavities with a very high quality factor, on the order of 106, giving polariton lifetimes of the order of 100 ps. When the polaritons are created with an incoherent pump, a dissipationless, coherent flow of the polaritons occurs over hundreds of microns, which increases as density increases. At high density, this flow is suddenly stopped, and the gas becomes trapped in a local potential minimum, with strong coherence.