Polariton superfluid

Polariton superfluid is predicted to be a state of the exciton-polaritons system that combines the characteristics of lasers with those of excellent electrical conductors. Researchers look for this state in a solid state optical microcavity coupled with quantum well excitons. The idea is to create an ensemble of particles known as exciton-polaritons and trap them. Wave behavior in this state results in a light beam similar to that from a laser but possibly more energy efficient.

Unlike traditional superfluids that need temperatures of approximately ~4 K, the polariton superfluid could in principle be stable at much higher temperatures, and might soon be demonstrable at room temperature.

Claims of the polariton superfluid appeared in the May 18, 2007, issue of the journal Science by David Snoke, an associate professor in the physics and astronomy department in the University of Pittsburgh School of Arts and Sciences. Snoke worked with University of Pittsburgh graduate students Ryan Balili and Vincent Hartwell on the project and their collaborators at the Bell Labs of Alcatel-Lucent in New Jersey.

Although several other researchers are working in the same field, the Pittsburgh group terminology and conclusions are not completely shared by them. In particular, important properties of superfluids, such as zero viscosity, and of lasers, such as perfect optical coherence, are a matter of debate. Although, there is some indication of quantized vortices when the pump beam has orbital angular momentum.

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