You can hear every event twice in a three-dimensional quantum gas

You would hear every event twice if you immersed yourself in a quantum fluid.

This is the first time that this property has been realized in a three-dimensional quantum gas. A Bose-Einstein Condensate can be formed by cooling a gas of potassium atoms trapped by laser beams in ultrahigh vacuum to less than a millionth of a degree above absolute zero temperature. In their experiment, they increase the interaction so much that the gas starts to move. They listen to two different sounds at different frequencies.

The Bose gas is a gas, not a liquid, because it is so large that it is not a liquid. The two-fluid model, which was developed in the 1940s, still describes their superfluid gas well. Condensed and non-condensed parts of the gas make up the majority of the fluids. The motion of the two parts is determined by the relative motion of the first and second sounds. The description of their gas is much simpler than the description of a liquid.

The paper is published in a journal.

More information: Timon A. Hilker et al, First and Second Sound in a Compressible 3D Bose Fluid, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.128.223601 Journal information: Physical Review Letters