Superconductivity and Superfluidity: a New Statistical Theory

A unified statistical theory of the 1957 BCS theory of superconductors (SCs) or superfluids with the 1925 theory of Bose-Einstein condensation (BEC) has finally been achieved. It reduces in the appropriate special cases to all the known statistical continuum (as opposed to -spin- or -lattice-) theories of SCs. The unified theory is based on a boson-fermion Hamiltonian reminiscent of the Fröhlich electron-phonon Hamiltonian, except that instead of phonons one has kinematically independent Cooper pairs (CPs) of both electrons (e) and of holes (h). It is now possible to depart from the perfect 2e-/2h-CP symmetry to which BCS theory is restricted by construction, and attain robustly high BEC transition temperatures to describe modern SCs, without abandoning electron-phonon inter-fermion dynamics.