Supersolids produced within Bose–Einstein condensates

Science News : Two teams of researchers have announced the creation of supersolids—matter that has a crystalline structure like a solid but can flow without friction like a superfluid. Both teams, one at MIT and the other at ETH Zürich, used the same general technique to produce the supersolids within Bose–Einstein condensates (BECs). Because a BEC is already a superfluid, the teams sought to create regular density variations within the material so it would also behave like a solid. Using lasers to push some of the atoms in the BEC, the MIT group created an interference pattern that resulted in alternating high- and low-density regions in the material. The ETH Zürich group created a similar regular pattern by placing a BEC inside two optical cavities in which light repeatedly bounces back and forth between sets of mirrors. Verification of either team’s result would be the first confirmed identification of a supersolid.