Thermoelectric transport in a two-dimensional Bose gas*

We demonstrate a new scheme to extract particle and energy flow induced by temperature gradients; equivalent to ``thermoelectricity'' in electronic materials. From in situ images, we analyze the density and energy redistribution of two-dimensional Bose gases in the presence of three-body inelastic collisions. We determine the thermopower and the Lorenz number, both showing interesting behavior in the quantum degenerate regime. Thermopower changes sign suggesting the emergence of superfluid counterflow; the Lorenz number approaches zero, contrasting with the Wiedermann-Franz law.