Hartree-Fock-Bogoliubov Theory of Polarized Fermi Systems...

Condensed Fermi systems with an odd number of particles can be described by means of polarizing external fields having a time-odd character. We illustrate how this works for Fermi gases and atomic nuclei treated by density functional theory or Hartree-Fock-Bogoliubov (HFB) theory. We demonstrate that by introducing two chemical potentials for different superfluid components, one can change the particle-number parity of the underlying quasiparticle vacuum. Formally, this method is a variant of non-collective cranking, and the procedure is equivalent to the so-called blocking. Relations between the two chemical potential methods and the cranking approximation for Fermi gases and nuclei are discussed.