Читать книгу Quantum Mechanics, Volume 3 - Claude Cohen-Tannoudji - Страница 108

A classical rotating fluid will always come to rest after a certain time, due to the viscous dissipation at the walls. In such a process, the macroscopic rotational kinetic energy of the whole fluid is progressively degraded into numerous smaller scale excitations, which end up simply heating the fluid. Will a rotating quantum fluid of repulsive bosons, described by a wave function χl(r), behave in the same way? Will it successively evolve towards the state χl – 1(r), then χl-2(r), etc., until it comes to rest in the state χ₀(r)?

We have seen in § 4-c of Complement C_XV that, to avoid the energy cost of fragmentation, the system always remains in a state where all the particles occupy the same quantum state. This is why we can use the Gross-Pitaevskii equation (18).