Fluctuation-damping of isolated, oscillating Bose-Einstein condensates
| Autor: | Johann Kroha, Anna Posazhennikova, Tim Lappe |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
Condensed Matter::Quantum Gases Quantum Physics Condensed Matter::Other FOS: Physical sciences Model parameters 01 natural sciences Omega 010305 fluids & plasmas law.invention Formalism (philosophy of mathematics) law Quantum Gases (cond-mat.quant-gas) Quantum mechanics Saddle point 0103 physical sciences 010306 general physics Condensed Matter - Quantum Gases Quantum Physics (quant-ph) Bose–Einstein condensate |
| DOI: | 10.48550/arxiv.1806.00376 |
| Popis: | Experiments on the nonequilibrium dynamics of an isolated Bose-Einstein condensate (BEC) in a magnetic double-well trap exhibit a puzzling divergence: While some show dissipation-free Josephson oscillations, others find strong damping. Such damping in isolated BECs cannot be understood on the level of the coherent Gross-Pitaevskii dynamics. Using the Keldysh functional-integral formalism, we describe the time-dependent system dynamics by means of a multi-mode BEC coupled to fluctuations (single-particle excitations) beyond the Gross-Pitaevskii saddle point. We find that the Josephson oscillations excite an excess of fluctuations when the effective Josephson frequency, $\tilde{\omega}_J$, is in resonance with the effective fluctuation energy, $\tilde{\varepsilon}_m$, where both, $\tilde{\omega}_J$ and $\tilde{\varepsilon}_m$, are strongly renormalized with respect to their noninteracting values. Evaluating and using the model parameters for the respective experiments describes quantitatively the presence or absence of damping. Comment: Phys Rev. A, published version, display of some figures improved, references corrected. 12 pages, 7 figures |
| Databáze: | OpenAIRE |
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