Exotic quantum state of matter created at room temperature, Digi Mart USA News: The laws of physics at the quantum level can break free from the standard confines of solids, liquids, and gases, and researchers have observed an exotic quantum state of matter, a particular way of particles organizing and behaving themselves.
What is more, it was engineered at room temperature, without the extreme cooling that quantum states usually require. The results of the experiments, carried out by an international team of researchers, have been published in Science Advances.
They point the way to more practical uses of quantum technology in advanced computing systems and sensors.
Part liquid and part solid, the quantum state was created using a tiny light-trapping structure called a microcavity. As a quantum testbed, the setup is relatively inexpensive, controllable via voltages, and does not need a cryogenic fridge.
“Our liquid-crystal microcavities can operate even at temperatures approaching 60 °C (140 °F),” says physicist Wiktor Piecek from the Military University of Technology in Poland.
The technical term for this quantum state is a supersolid in an exciton-polariton Bose-Einstein condensate. Two of the states that exist in the quantum realm are superfluids, which are liquids that can flow without resistance, and supersolids, which are superfluids with a regular, repeating crystal structure rather than a loose, fluid one.
That is the supersolid part.
The exciton-polariton is a hybrid quasiparticle, meaning multiple particles acting as one, combining both light and matter. A Bose-Einstein condensate is a state in which multiple particles or quasiparticles become a single quantum entity.
To produce this quantum state, the researchers combined a liquid crystal, which can be controlled by voltage, and an organic semiconductor, which interacts strongly with light. Laser pulses were then used to supply energy for the quantum reaction.
However, the behavior the scientists were looking for was relatively short-lived, as the materials degraded over time when the semiconductor reacted with the liquid crystal.
“We had to plan the entire sequence of experiments in advance,” says physicist Marcin Muszyński, from the City College of New York. “Repeating a measurement meant fabricating an entirely new sample.”
Further validation came with each successive laser pulse. The condensate reformed each time, with its stripes, the solid, crystal-like part of the supersolid, lining up in slightly different places with every refresh.
That is evidence of the inherent nature of this quantum state, rather than anything influenced by the external microcavity.
“This is a textbook example of spontaneous symmetry breaking,” says physicist Guillaume Malpuech, from the French National Centre for Scientific Research (CNRS). “Theory predicted that the supersolid could choose among several equivalent states, and that is exactly what we observed.”
While the individual particles produced by the researchers lasted only fractions of a second, it was enough to get the observations they needed. Multiple samples were tested with the same results, which were also backed up by computer simulation models.
Routes for developing the experiments further might involve finding ways to make the core reactions last longer and examining in more detail the quantum vortices that appeared, flaws in the stripe patterns that indicated superfluid behavior.
Ultimately, the work points to an easier method for studying quantum behavior in superfluids and supersolids, without the added expense and complexity of extreme cooling, particularly for the spin-orbit coupling shown here, the linking of light polarization and motion that created the supersolid arrangement.
Almost any quantum effect involving light, including those related to computer chips and advanced sensors, could benefit further down the line.
“Our work opens new perspectives for quantum fluids of light physics in the presence of spin-orbit coupling and beyond,” the researchers write in their published paper.
