Traditionally, we are familiar with three states of matter : solid, liquid, and gas. But in quantum physics, some substances are both solid and liquid. And even though scientists have been talking about supersolids since the 1950s, it wasn’t until 2020 that scientists from Italy, Germany and Innsbruck were able to independently detect them, in ultra-cold quantum gas.
Now, a team of researchers delves further into this question by being able to observe this new state of matter in a new dimension, a new milestone in fundamental physics.
What is a supersolid?
A supersolid is essentially a spatially ordered material with superfluid properties in condensed matter physics.
Researchers from the Department of Experimental Physics at the University of Innsbruck and the Institute for Quantum Optics and Quantum Information at the Austrian Academy of Sciences have precisely succeeded in creating supersolid states in ultracold quantum gases of magnetic atoms for the first time in history. This 2D supersolid is a seemingly contradictory type of matter that simultaneously has the properties of a solid and a superfluid.
“This demonstration is a key advance because a direct way to demonstrate that a system exhibits superfluidity is to study its properties under rotation, and this analysis cannot be achieved if the system has only one dimension”, the authors clarify in their study included in the Nature magazine.
Supersolids do not represent, therefore, an improved version of solids, but are solids whose atoms are arranged in a rigid crystalline structure, very similar to typical solids. But strangely, supersolids can also flow with zero viscosity, similar to a superfluid.
Previously, the most recent study presented supersolids with the help of another different state of matter, known as the Bose-Einstein condensate (BEC). These are composed of a cloud of low-density gas atoms cooled to temperatures close to absolute zero. At this very cold temperature, they exhibit puzzling quantum quirks not normally seen at these macro scales.
In ultracold quantum gas, the atoms organize themselves into droplets through their magnetic interaction and arrange themselves in a regular pattern.
“Normally, each atom would be expected to be in a particular droplet, with no possibility of swapping locations. But in the supersolid state, each particle is delocalized in all the drops, so it exists simultaneously in each drop “, comments Matthew Norcia, co-author of the work.
This strange formation allows the effect of superfluidity; a frictionless flow despite the existence of a spatial order . The basis of the new and growing field of investigation of supersolids is the strong polarity of magnetic atoms, whose interaction characteristics allow the creation of this paradoxical state of quantum mechanics of matter in the laboratory.
Referencias: Matthew A. Norcia, Claudia Politi, Lauritz Klaus, Elena Poli, Maximilian Sohmen, Manfred J. Mark, Russell N. Bisset, Luis Santos, Francesca Ferlaino. Two-dimensional supersolidity in a dipolar quantum gas. Nature, 2021; 596 (7872): 357 DOI: 10.1038 / s41586-021-03725-7
