A quantum Langevin equation for the amplitudes of the collective modes inBose-Einstein condensate is derived. The collective modes are coupled to athermal reservoir of quasi-particles, whose elimination leads to the quantumLangevin equation. The dissipation rates are determined via the correlationfunction of the fluctuating force and are evaluated in the local-densityapproximation for the spectrum of quasi-particles and the Thomas-Fermiapproximation for the condensate. I take great pleasure in dedicating thispaper to Gregoire Nicolis on the occasion of his sixtieth birthday.
展开▼
