Half-integer charge injection by a Josephson junction without excess noise

Physical review. B./Physical review. B, vol. 102

Abstract

A Josephson junction in a topological superconductor can inject a charge $e/2$ into a normal-metal contact, carried by chiral Majorana edge modes. Here, we address the question whether this half-integer charge is a sharp observable, without quantum fluctuations. Because the Majorana modes are gapless, they support charge fluctuations in equilibrium at zero temperature. But we find that the excess noise introduced out of equilibrium by the $e/2$ charge transfer vanishes. We discuss a strategy to reduce the equilibrium fluctuations, by means of a heavy-tailed time-dependent detection efficiency, to achieve a nearly noiseless half-integer charge transfer.

Authors 7

1. Fabian Hassler Aachen JARA-Institute for Quantum Information

   RWTH Aachen University

   Affiliation as printed

   JARA-Institute for Quantum Information, RWTH Aachen University, 52056 Aachen, Germany

2. Aurélien Grabsch Aachen Instituut-Lorentz

   Leiden University

   Affiliation as printed

   Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands

3. M. J. Pacholski Aachen Instituut-Lorentz

   Leiden University

   Affiliation as printed

   Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands

4. D. O. Oriekhov Aachen Instituut-Lorentz

   Leiden University · Taras Shevchenko National University of Kyiv

   Affiliation as printed

   Department of Physics, Taras Shevchenko National University of Kyiv, Kyiv 03680, Ukraine

   Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands

5. O. Ovdat Aachen Instituut-Lorentz

   Leiden University

   Affiliation as printed

   Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands

6. İnanç Adagideli

   Sabancı Üniversitesi · University of Twente

   Affiliation as printed

   Faculty of Engineering and Natural Sciences, Sabancı University, Orhanlı-Tuzla 34956, Turkey

   Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands

7. C. W. J. Beenakker Aachen Instituut-Lorentz

   Leiden University

   Affiliation as printed

   Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands