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Nonequilibrium noise and current fluctuations at the superconducting phase transition

Dmitry Bagrets and Alex Levchenko
Phys. Rev. B 90, 180505(R) – Published 24 November 2014

Abstract

We study non-Gaussian out-of-equilibrium current fluctuations in a mesoscopic NSN circuit at the point of a superconducting phase transition. The setup consists of a voltage-biased thin film nanobridge superconductor (S) connected to two normal-metal (N) leads by tunnel junctions. We find that, above a critical temperature, fluctuations of the superconducting order parameter associated with the preformed Cooper pairs mediate inelastic electron scattering that promotes strong current fluctuations. Though the conductance is suppressed due to the depletion of the quasiparticle density of states, higher cumulants of current fluctuations are parametrically enhanced. We identify an experimentally relevant transport regime where excess current noise may reach or even exceed the level of thermal noise.

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  • Received 15 July 2014
  • Revised 10 November 2014

DOI:https://doi.org/10.1103/PhysRevB.90.180505

©2014 American Physical Society

Authors & Affiliations

Dmitry Bagrets1 and Alex Levchenko2

  • 1Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
  • 2Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA

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Issue

Vol. 90, Iss. 18 — 1 November 2014

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