Quantum rain falls observed: Liquid behavior detected in ultracold gas
Surface tension is not just limited to normal liquids. It can also make ultracold atomic gases break into quantum droplets.
A team of European researchers has observed the spontaneous formation of droplets in an ultradilute quantum gas, driven by surface tension effects similar to those in classical liquids.
This is quite a rare phenomenon because quantum gases are millions of times less dense than liquids and typically lack the surface tension needed to hold droplets together. The formation of quantum droplets indicates that something highly unusual is happening at such low densities.
The findings could pave the way for new methods to control and manipulate quantum matter and contribute to the development of novel materials and quantum technologies.
Understanding the basics of surface tension
Before diving into the observation made by the researchers, you first need to understand three interconnected concepts.
The first is surface tension — a cohesive force at the surface of a liquid that pulls its molecules together, reducing the surface area. This occurs because molecules at the surface are attracted more strongly to each other than to the air above.