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TT: Fachverband Tiefe Temperaturen

TT 19: Quantum Liquids, Miscellaneous 2

TT 19.6: Vortrag

Montag, 11. März 2013, 16:15–16:30, H21

Damping of phase fluctuations in superfluid Bose gases — •Philipp Lange¹, Peter Kopietz¹, and Andreas Kreisel² — ¹Institut für Theoretische Physik, Universität Frankfurt, Max-von-Laue Strasse 1, 60438 Frankfurt, Germany — ²Department of Physics, University of Florida, 32611 Gainesville, FL, USA

Using Popov’s hydrodynamic approach we derive an effective Euclidean action for the long-wavelength phase fluctuations of superfluid Bose gases in D dimensions. We then use this action to calculate the damping of phase fluctuations at zero temperature as a function of D. For D>1 and small wavevectors k = |k| we find that, to leading order, the damping γ_k is proportional to A_D k^2D−1, where A_D is a constant prefactor that depends on the dimensionality. However, for D = 1 the coefficient A_D vanishes and one has to go beyond perturbation theory. Within a self-consistent calculation we find that in D=1 the damping acquires an additional power of k, leading to the long wavelength behavior γ_k ∝ k². In one dimension, we also calculate the entire spectral function of phase fluctuations.