Y. Takane, FLUCTUATIONS OF THE CRITICAL-CURRENT THROUGH JOSEPHSON-JUNCTIONS WITHDIRTY NORMAL-METAL BARRIERS, Journal of the Physical Society of Japan, 63(7), 1994, pp. 2668-2676
Josephson currents in superconductor-normal metal-superconductor junct
ions are studied numerically when the normal metal region is in the di
ffusive regime. The average critical current and the fluctuations of t
he critical current are calculated as a function of the length of the
normal metal region L. In the case where L is shorter than the coheren
ce length of the superconductor xi, the magnitude of the fluctuations
is shown to be of order eDELTA/hBAR (DELTA is the pair potential). Whe
n L is several times as long as xi, numerical results suggest that the
fluctuations become of order e square-root DELTAE(c)/hBAR (E(c) is th
e correlation energy). These results are compared with previous theore
tical studies.