Düsseldorf 2007 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 69: Photonik III
Q 69.1: Talk
Friday, March 23, 2007, 10:30–10:45, 5J
Asymmetrically pumped optical lattices: collective excitations and instability — •Janos Asboth1,2, Helmut Ritsch1, and Peter Domokos2 — 1Institut für Theoretische Physik, Univ. Innsbruck, Innsbruck, Österreich — 2Institute for Solid State Physics and Optics, Budapest, Hungary
We solve the self-consistent, coupled equations of motion for trapped atoms and the field of a one-dimensional optical lattice in the large detuning limit. In steady state the refractive index of the particles reduces the lattice constant, an effect, which is greatly enhanced if the lattice is formed by unbalanced pump beams. For pump asymmetry above a finite value, independent of the lattice size, no equilibrium configuration exists. Below this limit, the optomechanical coupling mediates collective oscillations of the particles around their steady state positions, which for asymmetric pumping take the form of traveling density waves. Above an asymmetry threshold, which decreases with the lattice size, these waves are amplified and the equilibrium becomes unstable, even in the presence of arbitrarily large viscous damping.