Universal Sound Diffusion in a Strongly Interacting Fermi Gas
Abstract
Transport of strongly interacting fermions governs modern materials -- from the high- cuprates to bilayer graphene --, but also nuclear fission, the merging of neutron stars and the expansion of the early universe. Here we observe a universal quantum limit of diffusivity in a homogeneous, strongly interacting Fermi gas of atoms by studying sound propagation and its attenuation via the coupled transport of momentum and heat. In the normal state, the sound diffusivity monotonically decreases upon lowering the temperature , in contrast to the diverging behavior of weakly interacting Fermi liquids. As the superfluid transition temperature is crossed, attains a universal value set by the ratio of Planck's constant and the particle mass . This finding of quantum limited sound diffusivity informs theories of fermion transport, with relevance for hydrodynamic flow of electrons, neutrons and quarks.
Cite
@article{arxiv.1909.02555,
title = {Universal Sound Diffusion in a Strongly Interacting Fermi Gas},
author = {Parth B. Patel and Zhenjie Yan and Biswaroop Mukherjee and Richard J. Fletcher and Julian Struck and Martin W. Zwierlein},
journal= {arXiv preprint arXiv:1909.02555},
year = {2020}
}