Quantum gases are ideally suited to study the microscopic results of matter interactions. Researchers at the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences and the University of Innsbruck, among other institutions, have realized a two-dimensional super-solid quantum gas in the laboratory for the first time.
Scientists can precisely control individual particles in clouds of very cold gas in the laboratory, revealing phenomena that cannot be observed in the everyday world. Two years ago, the research team produced the first super-solid state in an ultracold quantum gas of magnetic atoms. The supersolids have the typical properties of both a solid and a superfluid.
The researchers found that magnetic interactions cause the atoms to self-organize into droplets that follow a regular pattern. "Normally, you would think that each atom is in a particular droplet and there is no way to get between them." The team members said, "However, in the super-solid state, each particle is off-domain in all droplets and exists in every droplet at the same time." Despite the presence of spatial order (superfluidity), this exotic structure can produce effects such as frictionless flow.
But so far, the quantum gas supersolids produced by the researchers are just strings of droplets, meaning that these gas systems show supersolids in only one direction. By collaborating with researchers at multiple institutions, the team has demonstrated a two-dimensional extension of the super-solid nature by preparing super-solid dysprosium-atom quantum gases on either side of a structural phase transition. "We have extended this phenomenon to two dimensions, producing systems with two or more rows of liquid droplets." . This is not only a quantitative improvement, but also a significant broadening of the research perspective. For example, in a two-dimensional supersolid system, one can study how vortices form in the holes between several neighboring droplets.