Room-temperature supersolid created from light and matter
Physicists combine crystal structure with frictionless fluid flow inside an optical microcavity without extreme cooling.
Physicists from Poland, Switzerland and France have observed a quantum supersolid at room temperature, using hybrid particles of light and matter inside an optical microcavity. The scientific innovation, detailed in Science Advances by researchers from the University of Warsaw, removes the requirement for near absolute zero refrigeration in exploring this hybrid state of matter.
Merging crystal order with frictionless flow
Under classical physics, matter takes distinct forms: solids keep their crystalline order, while liquids flow. Quantum mechanics allows exceptions such as superfluidity, where a fluid moves through narrow openings without friction or viscosity. A supersolid pairs this frictionless motion with the repeating spatial lattice of a crystal. Theoretical physicists suggested this dual state in the 1960s, but laboratories only confirmed it in 2017 using ultracold atomic Bose-Einstein condensates, according to a report published by ScienceDaily. Those earlier setups required complex refrigeration hardware to chill atoms down to temperatures near absolute zero, posing a major hurdle for practical innovation.
“Our liquid-crystal microcavities can operate even at temperatures approaching 60°C”
— Professor Wiktor Piecek, Military University of Technology
Trapping exciton polaritons in a microcavity
To avoid cryogenic setups, the international TopoLight consortium turned to exciton polaritons, hybrid quasiparticles that emerge when photons interact strongly with matter inside a miniature optical chamber. These polaritons typically survive for just a few picoseconds, or trillionths of a second, but they still condense into a coordinated quantum superfluid. The team, which included researchers from the Faculty of Physics at the University of Warsaw, the Military University of Technology in Poland, IBM Research Zurich, and the French National Centre for Scientific Research (CNRS), tested an experimental prototype microcavity filled with an engineered liquid crystal and topped by an organic semiconductor layer.
Operation up to 60 degrees Celsius
The experimental setup proved resilient well above freezing points. "Our liquid-crystal microcavities can operate even at temperatures approaching 60°C," stated Professor Wiktor Piecek of the Military University of Technology, whose group developed the liquid crystal components, in the findings reported by ScienceDaily. At 60 degrees Celsius (approximately 140 degrees Fahrenheit), the system bypasses the bulky cooling infrastructure that previously restricted exotic quantum experiments to specialized low-temperature facilities.
Light fringes verify the dual state
Confirmation of the supersolid arrived in the patterns of light emitted by the sample. The condensate spontaneously formed regularly spaced bright fringes, revealing a periodic density modulation typical of a solid crystal. The bright fringes shifted positions with each new laser pulse, proving the arrangement was not a static defect locked into place. This optical invention demonstrates how hybrid quantum states can be stabilized under ambient conditions, which may aid development of optical computing devices and sensitive detectors, while paving the way for new patent filings in quantum photonics.
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