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

Abstract

Due to atomic 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 on the variance of that atom number. The result is obtained first using linearized time-dependent Bogoliubov-de Gennes equations, then in the Random Phase Approximation, and then it is generalized to beyond mean field. 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 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.

18 pages, 6 figures, to appear in Phys. Rev A

References in corpus (13)

• Theory of ultracold Fermi gases
• Vortices and Superfluidity in a Strongly Interacting Fermi Gas
• Nonlinear atom interferometer surpasses classical precision limit
• Weakly bound dimers of fermionic atoms
• The Equation of State of a Low-Temperature Fermi Gas with Tunable Interactions
• Long Phase Coherence Time and Number Squeezing of two Bose-Einstein Condensates on an Atom Chip
• Extension of Bogoliubov theory to quasi-condensates
• BCS-BEC Crossover and the Unitary Fermi Gas
• Integrated Mach-Zehnder interferometer for Bose-Einstein condensates
• Sign-free stochastic mean-field approach to strongly correlated phases of ultracold fermions
• Three fermions in a box at the unitary limit: universality in a lattice model
• Observation of interference between two molecular Bose-Einstein condensates
• Interferometric probe of paired states

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• Three-phonon and four-phonon interaction processes in a pair-condensed Fermi gas
• Spin-squeezed states for metrology
• Thermal blurring of a coherent Fermi gas
• Microscopic description of pair transfer between two superfluid Fermi systems: combining phase-space averaging and combinatorial techniques
• Single-particle versus many-body phase coherence in an interacting Fermi gas
• Phase spreading and temporal coherence of a pair-condensed Fermi gas at low temperature