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Distribution functions and current-correlations in normal-metal--superconductor hetero-structures

Thomas Gramespacher·Markus Buttiker
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Abstract

We introduce electron-like and hole-like distribution functions, which determine the currents and the fluctuation spectra of the currents measured at a normal-conductor--superconductor hetero-structure. These distribution functions are expressed with the help of newly defined partial densities of states for hetero-structures. Voltage measurements using a weakly coupled contact on such a structure show the absence of a contact resistance to the superconducting reservoir and illustrate how the interface to the superconductor acts as an Andreev mirror. We also discuss the current-current correlations measured at two normal contacts and argue that the appearance of positive correlations is a purely mesoscopic effect, which vanishes in the limit of a large number of channels and in the average over an ensemble.

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Thomas Gramespacher, Markus Buttiker. 1999-08-31. Distribution functions and current-correlations in normal-metal--superconductor hetero-structures. https://doi.org/10.1103/physrevb.61.8125

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