Stuttgart 2012 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 27: Quantengase: Optische Gitter 2
Q 27.7: Vortrag
Dienstag, 13. März 2012, 15:30–15:45, V53.01
Stability of (Super) Bloch Oscillations in the Presence of Time-Dependent Nonlinearities — •Christopher Gaul1, Elena Díaz1, Cord A. Müller2, Rodrigo Lima3, and Francisco Domínguez-Adame1 — 1GISC, Departamento de Física de Materiales, Universidad Complutense, E-28040 Madrid, Spain — 2Centre for Quantum Technologies, National University of Singapore, Singapore 117543, Singapore — 3Instituto de Física, Universidade Federal de Alagoas, Maceió AL 57072-970, Brazil
Bose-Einstein condensates (BECs) in optical lattices are employed to model fundamental problems of condensed-matter physics. Feshbach resonances can be used to arbitrarily modulate the s-wave scattering length, and by optical means the lattice potential can be accelerated back and forth (shaking). In presence of a constant force, the BEC performs Bloch oscillations (BOs). Here, we consider BOs in the presence of a time-modulated s-wave scattering length and/or in the presence of shaking. The beating of the shaking with the BO leads to so-called super-BO (SBO), with large amplitudes in real space.
Generically, the nonlinearity leads to dephasing and decay of the wave packet. Based on time-reversal symmetries, we find an infinite family of (harmonic) modulations that lead to a periodic time evolution of the wave packet, both for BOs [1] and for SBOs. In order to quantitatively describe the dynamics of (S)BOs in the presence of time-modulated nonlinearities, we employ collective coordinates and the linear stability analysis of an extended wave packet.
[1] Gaul et al. PRL 102, 255303 (2009), PRA 84, 053627 (2011)