Quantum nondemolition measurement of a kicked qubit

Andrew N. Jordan and Markus Büttiker
Phys. Rev. B 71, 125333 – Published 29 March 2005

Abstract

We propose a quantum nondemolition measurement using a kicked two-state system (qubit). By tuning the waiting time between kicks to be the qubit oscillation period, the kicking apparatus performs a nondemolition measurement. While dephasing is unavoidable, the nondemolition measurement can (1) slow relaxation of diagonal density matrix elements, (2) avoid detector back-action, and (3) allow for a large signal-to-noise ratio. Deviations from the ideal behavior are investigated by allowing for detuning of the waiting time, as well as finite-time, noisy pulses. The scheme is illustrated with a double-dot qubit measured by a gate-pulsed quantum point contact.

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  • Received 25 June 2004

DOI:https://doi.org/10.1103/PhysRevB.71.125333

©2005 American Physical Society

Authors & Affiliations

Andrew N. Jordan and Markus Büttiker

  • Département de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland

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Issue

Vol. 71, Iss. 12 — 15 March 2005

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