Universal density shift coefficients for the thermal conductivity and shear viscosity of a unitary Fermi gas

We measure universal temperature-independent density shifts for the thermal conductivity <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>κ</a:mi><a:mi>T</a:mi></a:msub></a:math> and shear viscosity <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mi>η</b:mi></b:math>, relative to the high temperature limits, for a normal phase unitary Fermi gas confined in a box potential. We show that a time-dependent kinetic theory model enables extraction of the hydrodynamic transport times <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>τ</c:mi><c:mi>η</c:mi></c:msub></c:math> and <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:msub><d:mi>τ</d:mi><d:mi>κ</d:mi></d:msub></d:math> from the time-dependent free decay of a spatially periodic density perturbation, yielding the static transport properties and density shifts, corrected for finite relaxation times. Published by the American Physical Society 2024