Seminarium Fizyki Materii Skondensowanej

I will discuss recent theoretical and experimental progress in understanding nonequilibrium dynamics of interacting Bose condensates, in particular their collective modes and transport: i) We report the first detection of the Higgs-type amplitude mode using Bragg spectroscopy in a strongly interacting Bose condensate in an optical lattice. By comparison of our experimental data with a spatially resolved, dynamical Gutzwiller calculation, we obtain good quantitative agreement. This allows for a clear identification of the amplitude mode, showing that it can be detected with full momentum resolution by going beyond the linear response regime. A systematic shift of the sound and amplitude modes' resonance frequencies due to the finite Bragg beam intensity is observed. II) We consider a neutral spinor condensate moving in a periodic magnetic field. The spatially varying magnetic field induces an effective spin-dependent Lorentz force which in turn gives rise to a spin-dependent Hall effect. Simulations of the Gross-Pitaevskii equation quantify the Hall effect. We discuss possible experimental realizations.