Model of qubits as devices to detect the third moment of current fluctuations

Valentina Brosco, Rosario Fazio, F. W. J. Hekking, and J. P. Pekola
Phys. Rev. B 74, 024524 – Published 27 July 2006

Abstract

Under appropriate conditions, controllable two-level systems can be used to detect the third moment of current fluctuations. We derive a master equation for a quantum system coupled to a bath valid to the third order in the coupling between the system and the environment. In this approximation the reduced dynamics of the quantum system depends on the frequency-dependent third moment. Specializing to the case of a controllable two-level system (a qubit) and in the limit in which the splitting between the levels is much smaller than the characteristic frequency of the third moment, it is possible to show that the decay of the qubit has additional oscillations whose amplitude is directly proportional to the value of the third moment. We discuss an experimental setup where this effect can be seen.

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  • Received 10 April 2006

DOI:https://doi.org/10.1103/PhysRevB.74.024524

©2006 American Physical Society

Authors & Affiliations

Valentina Brosco1, Rosario Fazio2,3, F. W. J. Hekking4, and J. P. Pekola5

  • 1NEST-CNR-INFM & Dipartimento di Fisica, Universitá di Pisa, largo E. Fermi, I-56100 Pisa, Italy
  • 2International School for Advanced Studies (SISSA), Via Beirut 2-4, I-34014 Trieste, Italy
  • 3NEST-CNR-INFM & Scuola Normale Superiore, piazza dei Cavalieri 7, I-56126 Pisa, Italy
  • 4Laboratoire de Physique et Modélisation des Milieux Condensés Magistère-CNRS, Boîte Postale 166, 38042 Grenoble Cedex 9, France
  • 5Low Temperature Laboratory, Helsinki University of Technology, P.O. Box 3500, FIN-02015 HUT, Finland

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Issue

Vol. 74, Iss. 2 — 1 July 2006

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