Eur. Phys. J. D 8, 319-332 (2000)
https://doi.org/10.1007/s100530050042

Binary mixtures of Bose-Einstein condensates: Phase dynamics and spatial dynamics

Laboratoire Kastler Brossel (Unité de recherche de l'École Normale Supérieure et de l'Université Pierre et Marie Curie, associée au CNRS.) , 24 rue Lhomond, 75231 Paris Cedex 5, France

Received: 23 April 1999
Revised: 21 September 1999
Published online: 15 March 2000

Abstract

We investigate the relative phase coherence properties and the occurrence of demixing instabilities for two mutually interacting and time evolving Bose-Einstein condensates in traps. Our treatment naturally includes the additional decoherence effect due to fluctuations in the total number of particles. Analytical results are presented for the breathe-together solution, an extension of previously known scaling solution to the case of a binary mixture of condensates. When the three coupling constants describing the elastic interactions among the atoms in the two states are close to each other, a dramatic increase of the phase coherence time is predicted. Numerical results are presented for the parameters of the recent JILA experiments.