1307.7479 (Hadrien Kurkjian et al.)

Phase operators and blurring time of a pair-condensed Fermi gas    [PDF]

Hadrien Kurkjian, Yvan Castin, Alice Sinatra

Due to interactions and dispersion in the total atom number, the order parameter of a pair-condensed Fermi gas experiences a collapse in a time that we derive microscopically. As in the bosonic case, this blurring time depends on the derivative of the gas chemical potential with respect to the atom number and to the variance of that atom number. The result is obtained first within a semi-classical theory using linearized Bogoliubov-de Gennes equations, then in the Random Phase Approximation, then it is generalized to beyond mean field approximation. In this framework, we construct and compare two phase operators for the paired fermionic field: The first one, issued from our study of the dynamics, is the infinitesimal generator of adiabatic translations in the total number of pairs. The second one is simply the phase operator of the amplitude of the field of pairs on the condensate mode. We explain that these two operators differ due to the dependence of the condensate wave function on the atom number.

View original: http://arxiv.org/abs/1307.7479