Fluctuation dispersion of transport coefficients in a Bose superfluid

V. G. Morosov

T. R. Kirkpatrick, J. R. Dorfman

Brandon Anderson, Chien‐Te Wu, Rufus Boyack +1 more

Wittaya Kanchanapusakit

The thermal fluctuations of the order parameter affect the transport of Bose gas above the superfluid transition. Using the time-dependent Ginzburg-Landau theory in the classical region, we calculate the fluctuation corrections to the coefficients of thermal conductivity and shear viscosity. Above the transition temperature T c , the fluctuation contribution to the thermal conductivity diverges as ( T − T c ) -2+ d /2 for dimensions d . The viscosity drops near T c since the fluctuation contributes a correction which varies as − ( T − T c ) −2+ d /2 . The calculations are conducted under the condition that the fluctuation corrections are small compared with the normal part of the transport coefficients.

Adam Rançon, Cheng Chin, Kathryn Levin

We discuss the general principles of transport in normal phase atomic gases, comparing Bose and Fermi systems. Our study shows that two-dimensional bosonic transport is non-universal with respect to different dissipation mechanisms. Near the superfluid transition temperature T c , a striking similarity between the fermionic and bosonic transport emerges because super-conducting (fluid) fluctuation transport for Fermi gases is dominated by the bosonic, Cooper pair component. As in fluctuation theory, one finds that the Seebeck coefficient changes sign at T c and the Lorenz number approaches zero at T c . Our findings appear quantitatively consistent with recent Bose gas experiments.

P. Lange, Peter Kopietz, Andreas Kreisel