In a dilute Bose gas the interaction between the normal gas and the condensate can be studied both at equilibrium and for its relevance to superfluid mechanics. In this article, one reviews first the thermodynamics of the interacting Bose gas in the low density limit and in the low temperature–finite density case. This is extended to thermodynamics with a velocity difference between the two components, normal and superfluid. It is argued that, if the initial value of the momentum related to this velocity difference is larger than the one given by thermodynamic stability, a new condensate should form in a finite time with a velocity close to the that of the normal gas. In the dilute case this occurrence of a new condensate is reminiscent of the condensation in the isotropic case at high enough density.
Dans un gaz de Bose dilué l'interaction entre gaz normal et condensat est étudiée à la fois pour l'équilibre et dans le cas d'un écoulement superfluide. On revoit d'abord la thermodynamique d'un gaz de Bose dilué et aussi le cas d'un fluide à base température. Les résultats sont étendus à la thermodynamique avec différence de vitesse. Si la vitesse relative entre les deux composantes excède la valeur limite de stabilité thermodynamique, un nouveau condensat doit se former avec une vitesse proche de celle du gaz normal. Dans le cas d'un gaz dilué cette apparition d'un nouveau condensat rappelle la condensation dans le cas isotrope à densité suffisante.
Mots-clés : Gaz de Bose, Gaz de Bose dilué, Thermodynamique d'un fluide à base température
Yves Pomeau 1
@article{CRPHYS_2004__5_1_39_0, author = {Yves Pomeau}, title = {Normal fluid/condensate interaction}, journal = {Comptes Rendus. Physique}, pages = {39--47}, publisher = {Elsevier}, volume = {5}, number = {1}, year = {2004}, doi = {10.1016/j.crhy.2004.01.011}, language = {en}, }
Yves Pomeau. Normal fluid/condensate interaction. Comptes Rendus. Physique, Bose-Einstein condensates: recent advances in collective effects, Volume 5 (2004) no. 1, pp. 39-47. doi : 10.1016/j.crhy.2004.01.011. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2004.01.011/
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