Time-Dependent Density-Functional Theory for Superfluids
M. L. Chiofalo, M. P. Tosi
Abstract
A density-functional theory is established for inhomogeneous superfluids at finite temperature, subject to time-dependent external fields in isothermal conditions. After outlining parallelisms between a neutral superfluid and a charged superconductor, Hohenberg-Kohn-Sham-type theorems are proved for gauge-invariant densities and a set of Bogolubov-Popov equations including exchange and correlation is set up. Earlier results applying in the linear response regime are recovered. 1 Experiments on confined Bose-condensed gases have revealed a rich variety of dynamical behaviours. These include elementary excitations of lowlying shape deformation modes [1], propagation of sound waves in both the condensate and the thermal cloud [2], Josephson-like oscillations in double condensates [3], creation of vortices [4], phase dynamics from various atomlaser configurations [5] and Bloch oscillations of a condensate in an optical