Resonant Cooper-Pair Tunneling: Quantum Noise and Measurement Characteristics

A. A. Clerk, S. M. Girvin, A. K. Nguyen, and A. D. Stone
Phys. Rev. Lett. 89, 176804 – Published 8 October 2002

Abstract

We study the quantum charge noise and measurement properties of the double Cooper-pair resonance point in a superconducting single-electron transistor (SSET) coupled to a Josephson charge qubit. Using a density-matrix approach for the coupled system, we obtain a full description of the measurement backaction; for weak coupling, this is used to extract the quantum charge noise. Unlike the case of a nonsuperconducting SET, the backaction here can induce population inversion in the qubit. We find that the Cooper-pair resonance process allows for a much better measurement than a similar nonsuperconducting SET, and can approach the quantum limit of efficiency.

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  • Received 15 March 2002

DOI:https://doi.org/10.1103/PhysRevLett.89.176804

©2002 American Physical Society

Authors & Affiliations

A. A. Clerk, S. M. Girvin, A. K. Nguyen, and A. D. Stone

  • Department of Applied Physics and Physics, Yale University, New Haven, Connecticut, 06511

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Issue

Vol. 89, Iss. 17 — 21 October 2002

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