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We analyze nonperturbatively the behavior of a Josephson junction in which two BCS superconductors are coupled through an Anderson impurity. We recover earlier perturbative results which found that a 0ex{0ex}=0ex{0ex} phase difference is preferred when the impurity is singly occupied and the on-site Coulomb interaction is large. We find a novel intermediate phase in which one of 0ex{0ex}=0ex{0ex}0 and 0ex{0ex}=0ex{0ex} is stable while the other is metastable, with the energy E () having a kink somewhere in between. As a consequence of the kink, the I-V characteristics of the junction are modified at low voltages.
Rozhkov et al. (Mon,) studied this question.