Why Shot Noise Does Not Generally Detect Pairing in Mesoscopic Superconducting Tunnel Junctions

Physical Review Letters, vol. 132, pp. 076001

Abstract

The shot noise in tunneling experiments reflects the Poissonian nature of the tunneling process. The shot-noise power is proportional to both the magnitude of the current and the effective charge of the carrier. Shot-noise spectroscopy thus enables us, in principle, to determine the effective charge q of the charge carriers of that tunnel. This can be used to detect electron pairing in superconductors: In the normal state, the noise corresponds to single electron tunneling (q=1e), while in the paired state, the noise corresponds to q=2e. Here, we use a newly developed amplifier to reveal that in typical mesoscopic superconducting junctions, the shot noise does not reflect the signatures of pairing and instead stays at a level corresponding to q=1e. We show that transparency can control the shot noise, and this q=1e is due to the large number of tunneling channels with each having very low transparency. Our results indicate that in typical mesoscopic superconducting junctions, one should expect q=1e noise and lead to design guidelines for junctions that allow the detection of electron pairing.

Authors 12

1. Jiasen Niu Aachen

   Leiden University

   Affiliation as printed

   Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands

2. Koen M. Bastiaans

   Delft University of Technology

   Affiliation as printed

   Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands

3. Jian-Feng Ge Aachen

   Leiden University

   Affiliation as printed

   Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands

4. John Jesudasan

   Tata Institute of Fundamental Research

   Affiliation as printed

   Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India

5. Pratap Raychaudhuri

   Tata Institute of Fundamental Research

   Affiliation as printed

   Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India

6. Max Karrer

   University of Tübingen

   Affiliation as printed

   Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, Universität Tübingen, D-72076 Tübingen, Germany

7. R. Kleiner

   University of Tübingen

   Affiliation as printed

   Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, Universität Tübingen, D-72076 Tübingen, Germany

8. D. Koelle

   University of Tübingen

   Affiliation as printed

   Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, Universität Tübingen, D-72076 Tübingen, Germany

9. A. Barbier

   Institut de Radioastronomie Millimétrique

   Affiliation as printed

   Institut de Radioastronomie Millimétrique (IRAM), Domaine Universitaire de Grenoble, 38400 Saint-Martin-d’Hères, France

10. E. F. C. Driessen

    Institut de Radioastronomie Millimétrique

    Affiliation as printed

    Institut de Radioastronomie Millimétrique (IRAM), Domaine Universitaire de Grenoble, 38400 Saint-Martin-d’Hères, France

11. Yaroslav M. Blanter

    Delft University of Technology

    Affiliation as printed

    Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands

12. Milan P. Allan Aachen

    Leiden University · Munich Center for Quantum Science and Technology · Ludwig-Maximilians-Universität München

    Affiliation as printed

    Fakultät für Physik, Ludwig-Maximilians-Universität, Schellingstrasse 4, München 80799, Germany

    Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands

    Munich Center for Quantum Science and Technology (MCQST), München, Germany