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TT: Fachverband Tiefe Temperaturen

TT 37: Matter At Low Temperature: Quantum Liquids, Bose-Einstein Condensates, Ultra-cold Atoms, ... 2

TT 37.7: Talk

Thursday, March 29, 2012, 11:00–11:15, H 3005

Localized phase structures growing out of quantum fluctuations in two tunnel-coupled atomic condensates — •Clemens Neuenhahn¹, Anatoli Polkovnikov², and Florian Marquardt¹ — ¹Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute for Theoretical Physics II, Staudtstr. 7, 91058 Erlangen, Germany — ²Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA

We investigate the relative phase between two weakly interacting 1D condensates of bosonic atoms after suddenly switching on the tunnel-coupling. The following phase dynamics is governed by the quantum sine-Gordon equation. In the semiclassical limit of weak interactions, we observe the parametric amplification of zero-point quantum fluctuations leading to the formation of breathers with a finite lifetime. The typical lifetime and density of the these 'quasibreathers' are derived employing exact solutions of the classical sine-Gordon equation. Both quantities (density and lifetime) depend crucially on the initial, overall relative phase between the condensates, which is considered as a tunable parameter.