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VOLUME 59 (1994) | ISSUE 12 |
PAGE 821
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Nonequilibrium noise in a mesoscopic conductor: A microscopic analysis
Altshuler B. L., Levitov L. S., Yakovets A. Yu.
Current fluctuations are studied in a mesoscopic conductor using the nonequilibrium Keldysh technique. A general expression is derived for the fluctuations in the presence of a time-dependent voltage, which is valid for arbitrary relation between voltage and temperature. Two limits are then considered: a voltage pulse and a dc voltage. A voltage pulse causes phase-sensitive current fluctuations, for which we derive microscopically an expression periodic in fV(t)dt with a period hie. 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 obtain quantum-to-classical shot noise reduction factor 1/3, in agreement with recent results of Beenakker and Biittiker.
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