A Study by Swinburne University of Technology published this week examines the propagation of energy as sound waves in quantum gas, revealing for the first time sturdy variations in the nature of the sound wave as a perform of temperature.
At low energies, this energy travels by way of the collective movement of many particles shifting in sync—essentially, as sound waves—quantified utilizing quasiparticles known as phonons.
Below the superfluid transition temperature Tc these sound waves in a unitary Fermi gas can propagate without collisions and are pushed by ripples in the section of the superfluid order parameter (wave-function)—this mode is named the Bogoliubov-Anderson (BA) phonon.
Sturdy similarities had been recognized within the temperature dependence of sound in the unitary Fermi gasoline and the behavior of phonons in liquid helium, which was one of the first superfluids recognized historically.
The ultracold atomic gases formed and studied in Prof Chris Vale’s lab at Swinburne enable very precise tuning of interactions between atoms.
In a unitary gas, elastic collisions change into resonant, and the thermodynamic properties of the gas become universal functions of the temperature and density. Unitary Fermi gases enable precise testing of theories of interacting fermions.
The crew then studied excitations in the gasoline above and below the superfluid section transition Tc utilizing two-photon Bragg spectroscopy.