Generally, matter exists in three distinct forms: as a solid, a liquid or a gas. Past physics research, however, has unveiled other curious states of matter, one of which is supersolidity. In a supersolid state, particles are arranged into a rigid crystal and can nonetheless flow through the solid without any friction. Although this may appear contradictory, this state is allowed by the laws of quantum mechanics.
A team of researchers at Aarhus University in Denmark has recently carried out a study exploring supersolidity in dipolar Bose-Einstein condensates (BEC), states of matter in which separate atoms cooled to near absolute zero unite into a single quantum mechanical entity. Their study, featured in Physical Review Letters, unveiled a critical point at which crystallization occurs, and a new supersolid phase emerges, which is characterized by a regular honeycomb pattern with near-perfect superfluidity.
"Conjectured more than 50 years ago, supersolidity has remained elusive to observations until recently, where new promise is given by experiments with very dilute gases of atoms that are cooled and trapped by laser light at temperatures near absolute zero," Thomas Pohl, one of the researchers who carried out the study, told Phys.org. "Under such extreme conditions, the atoms can collectively form a so-called Bose-Einstein condensate, which is a quantum state that represents an ideal frictionless superfluid. However, one would naturally not expect that such a dilute, free-flowing liquid can crystallize. Fascinated by the bizarre nature of the supersolid state, we wanted to understand whether this might nevertheless be possible if the atoms interacted in a suitable way."
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