Non-diffusive phase spreading of a Bose-Einstein condensate at finite temperature

Alice Sinatra (1) , Yvan Castin (1) , Emilia Witkowska (2)

1 LKB (Lhomond) - Laboratoire Kastler Brossel
2 Institute of Physics

We show that the phase of a condensate in a finite temperature gas spreads linearly in time at long times rather than in a diffusive way. This result is supported by classical field simulations, and analytical calculations which are generalized to the quantum case under the assumption of quantum ergodicity in the system. This super-diffusive behavior is intimately related to conservation of energy during the free evolution of the system and to fluctuations of energy in the prepared initial state.

Mots clés: Bose-Einstein condensate; phase spreading; finite temperature; coherence time; matter waves

Domaines: Autre [cond-mat.other]; Physique Quantique [quant-ph]

Alice Sinatra, Yvan Castin, Emilia Witkowska. Non-diffusive phase spreading of a Bose-Einstein condensate at finite temperature. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2007, 75, pp.0033616. ⟨10.1103/PhysRevA.75.033616⟩. ⟨hal-00109021v3⟩