Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 15: MLT: Quantum Liquids, Bose-Einstein Condensates, Ultra-cold Atoms, ... 1

TT 15.5: Talk

Tuesday, March 23, 2010, 15:15–15:30, H18

Bogoliubov excitations in correlated disorder potentials — •Christopher Gaul and Cord A. Müller — Physikalisches Institut, Universität Bayreuth, Deutschland

Bogoliubov excitations carry precious information about the properties of disordered Bose-Einstein condensates. By a saddle-point expansion of the Gross-Pitaevskii energy functional around the disorder-modified ground state, we derive the effective Hamiltonian for the Bogoliubov excitations [1]. Expectation values of physically interesting quantities are obtained by weak-disorder perturbation theory in the Nambu formalism. We extend previous work in the hydrodynamic regime [2] and compute the disorder-broadened dispersion relation for arbitrary condensate healing length, disorder correlation length and excitation wavelength. Observable disorder-induced effects are predicted for the excitation lifetime and localization length, their speed of sound and average density of states.

[1] Gaul and Müller, Europhys. Lett., 83, 10006 (2008)

[2] Gaul, Renner and Müller, Phys. Rev. A, 80, 053620 (2009)