Hannover 2016 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 61: Quantum Gases: Fermions II
Q 61.3: Vortrag
Freitag, 4. März 2016, 11:30–11:45, e001
Detecting the BCS order parameter in the dephasing of collective oscillations after a sudden ramp of the lattice depth in a honeycomb lattice — •Marlon Nuske1, Eite Tiesinga2, and Ludwig Mathey1 — 1Zentrum für Optische Quantentechnologien and Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany — 2Joint Quantum Institute and Center for Quantum Information and Computer Science, National Institute of Standards and Technology and University of Maryland, Gaithersburg, Maryland 20899, USA
We obtain the excact time evolution for a mean-field Bardeen-Cooper-Schrieffer (BCS) state after a sudden quench to a large lattice depth, where the dynamics is dominated by interactions between atoms. The quench initiates collective oscillations with frequency Uf/(2π) of the momentum occupation numbers and imprints a phase oscillating with the same frequency on the order parameter. Finite hopping after the quench leads to dephasing of the different momentum modes and a subsequent damping of the oscillations. Even for finite temperatures this occurs for a mean-field BCS state, but not for a non-interacting Fermi gas. Measuring the dephasing of collective oscillations of occupation numbers may therefore be used as a signature to detect the BCS order parameter Δ. Finally, we investigate the time evolution of the density-density correlations.