Andreev levels in a single-channel conductor
arXiv:cond-mat/0103445 · doi:10.1103/PhysRevB.64.134206
Abstract
We calculate the subgap density of states of a disordered single-channel normal metal connected to a superconductor at one end (NS junction) or at both ends (SNS junction). The probability distribution of the energy of a bound state (Andreev level) is broadened by disorder. In the SNS case the two-fold degeneracy of the Andreev levels is removed by disorder leading to a splitting in addition to the broadening. The distribution of the splitting is given precisely by Wigner's surmise from random-matrix theory. For strong disorder the mean density of states is largely unaffected by the proximity to the superconductor, because of localization, except in a narrow energy region near the Fermi level, where the density of states is suppressed with a log-normal tail.
12 pages, 5 figures
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