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VOLUME 59 (1994) | ISSUE 12 |
PAGE 821
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Non-equilibrium noise in a mesoscopic conductor: microscopic analysis
Altshuler B.L., Levitov L.S., Yakovets A.Yu.
Current fluctuations are studied in a mesoscopic conductor using non-equilibrium Keldysh technique. We derive a general expression for the fluctuations in the presence of a time dependent voltage, valid for arbitrary relation between voltage and temperature. Two limits are then treated: a pulse of voltage and a DC voltage. A pulse of voltage causes phase sensitive current fluctuations for which we derive microscopically an expression periodic in J V(t)dt with the period h/e. Applied to current fluctuations in Josephson circuits caused by phase slips, it gives an anomalous contribution to the noise with a logarithmic singularity near the critical current. In the DC case, we get quantum to classical shot noise reduction factor 1/3, in agreement with recent results of Beenakker and Buttiker.
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