Physicists have achieved a groundbreaking feat by transforming a superfluid into a supersolid and back again, marking the first time such a transition has been observed. This remarkable discovery challenges our understanding of quantum matter and opens up new frontiers in research.
In a recent study published in the journal Nature, scientists witnessed a fascinating phenomenon: a group of quasiparticles called excitons, which are essentially combinations of electrons and electron holes, transitioning from a superfluid to a supersolid state and then back again. This reversible phase transition, akin to water turning from a liquid to ice and back, is a significant breakthrough in the field of quantum physics.
Unveiling Hidden Matter Phases
While we're accustomed to the three common states of matter (gases, liquids, and solids), there are numerous other phases that exist under extreme conditions. Superfluids, for instance, are a unique state that occurs when particles like helium isotopes and excitons are cooled to just above absolute zero, the point where all heat ceases to exist. Superfluids exhibit zero viscosity and form quantum vortices when stirred, resembling tiny eternal tornadoes.
Supersolids, on the other hand, are a theoretical state of matter that emerges when superfluids are cooled even further. They retain the zero viscosity of superfluids but arrange particles in an orderly structure, similar to a crystal lattice, while still allowing flow and the formation of quantum vortices. While supersolids have been created in labs using additional equipment and energy, this new study showcases a natural phase transition.
The study, conducted by researchers at Columbia University, involved placing two pieces of graphene, thin sheets of carbon atoms, very close together and applying a strong magnetic field while cooling the system. This process resulted in the formation of an exciton 'soup.' When cooled to specific temperatures, the excitons transformed into a superfluid, and further cooling led to a mysterious electrically insulative phase, which the team suspects is the theorized supersolid state.
Challenging Conventional Understanding
Jia Li, a physicist at the University of Texas at Austin and co-author of the study, emphasized the significance of observing an insulating phase that transitions into a superfluid, suggesting that the low-temperature phase is a highly unusual exciton solid. The team is now exploring other materials and developing new methods to measure and study the supersolid state, aiming to deepen our understanding of particle physics and potentially harness the properties of higher-temperature supersolids for practical applications.
