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Quantum Nondemolition Measurement of a Kicked Qubit

Andrew N. Jordan·Markus Buttiker
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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 studied 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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Andrew N. Jordan, Markus Buttiker. 2004-06-22. Quantum Nondemolition Measurement of a Kicked Qubit. https://doi.org/10.1103/physrevb.71.125333

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