Thermography of the superfluid transition in a strongly interacting Fermi gas. (https://pubmed.ncbi.nlm.nih.gov/38330124/)

These scientists wanted to study how heat moves in different types of matter. They were particularly interested in a special type of matter called a superfluid. In a normal liquid, when there is a hot spot, the heat spreads out slowly. But in a superfluid, the heat moves like a wave called "second sound".

It is not easy to directly see how heat moves, so scientists usually have to find other ways to measure it. In this study, the scientists used a special type of imaging called thermography. They used a type of gas made up of tiny particles called atoms, and they made the gas very cold. By using a special type of radio wave, they were able to measure the temperature of the gas with very high precision, even smaller than a billionth of a degree.

The scientists observed that when the gas changed from a normal liquid to a superfluid, there was a sudden change in how the heat moved. They could see this change by looking at the radio wave measurements. They also found that when the gas was in the superfluid state, there was a peak in how the heat wave moved.

By using this method, the scientists were able to learn a lot about how heat and density (how tightly packed the atoms are) behave in the superfluid gas. This helps us understand the special properties of superfluids and how they move.

Yan Z., Patel PB., Mukherjee B., Vale CJ., Fletcher RJ., Zwierlein MW. Thermography of the superfluid transition in a strongly interacting Fermi gas. Science. 2024 Feb 9;383(6683):629-633. doi: 10.1126/science.adg3430. Epub 2024 Feb 8.