Matrix elements of one-body and two-body operators between arbitrary HFB multi-quasiparticle states

We present new formulae for the matrix elements of one-body and two-body physical operators, which are applicable to arbitrary Hartree-Fock-Bogoliubov wave functions, including those for multi-quasiparticle excitations. The testing calculations show that our formulae may substantially reduce the computational time by several orders of magnitude when applied to many-body quantum system in a large Fock space.