ANDREEV CURRENT-INDUCED BOUND-STATES IN SUPERCONDUCTING JUNCTIONS

For superconducting tunneling and point contacts, we predict a new type of excitations belonging to the discrete spectrum. These excitations have the nature of the Andreev bound states in SNS systems. They appear due to the influence of supercurrent simultaneously with a potential well near the weak link. For a given current there is only one discrete level the energy of which is calculated by means of a rigorous solution of the Bogolyubov - de Gennes equations. For a symmetric contact, the current-induced Andreev bound states are formed with an arbitrary small phase difference phi while in the asymmetric case the condition \phi\ greater-than-or-equal-to arc cos DELTA-1/DELTA-2 is to be met (DELTA-1, DELTA-2 being the energy gaps of the left and right superconductors, respectively). There are an analogous critical condition for a one-dimensional asymmetric potential well in the quantum mechanics and that for an asymmetric superconducting junction S1NS2, discussed in the Appendix.