The superfluid-like behaviour of a condensate of polaritons at room temperature has been seen for the first time by researchers in Italy and Canada. Until now, such behaviour had only been observed at very low temperatures. As well as allowing physicists to study macroscopic quantum phenomena under ambient conditions, the research could be exploited in the development of photonic circuits that use light to process information.
Superfluidity – the flow of liquid without any friction – was first observed in ultracold liquid helium in 1938. Such a superfluid liquid can creep up along the walls of a container, boil without bubbles and even flow around obstacles. Shortly after the discovery, the physicist Fritz London suggested that there might be some sort of link between a superfluid and a Bose–Einstein condensate (BEC) – the latter being a state of matter in which all constituent particles have condensed into a single quantum state. He was proved right in 1995 when superfluidity was observed in BECs made from ultracold atoms.
To date, however, superfluidity and BECs have only been observed at very low temperatures. A team led by Daniele Sanvitto of the CNR NANOTEC in Leece, Italy, and Stéphane Kéna-Cohen of the Polytechnqiue Montréal in Canada has now shown that a condensate of quasiparticles called polaritons can behave as a superfluid at room temperature.
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