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arXiv · 0808.0464

Role of relaxation in the quantum measurement of a superconducting qubit using a nonlinear oscillator

T. Picot·A. Lupascu·S. Saito·C. J. P. M. Harmans·J. E. Mooij
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Abstract

We analyze the relaxation of a superconducting flux qubit during measurement. The qubit state is measured with a nonlinear oscillator driven across the threshold of bifurcation, acting as a switching dispersive detector. This readout scheme is of quantum non-demolition type. Two successive readouts are used to analyze the evolution of the qubit and the detector during the measurement. We introduce a simple transition rate model to characterize the qubit relaxation and the detector switching process. Corrected for qubit relaxation the readout fidelity is at least 95%. Qubit relaxation strongly depends on the driving strength and the state of the oscillator.

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T. Picot, A. Lupascu, S. Saito, C. J. P. M. Harmans, J. E. Mooij. 2008-09-30. Role of relaxation in the quantum measurement of a superconducting qubit using a nonlinear oscillator. https://doi.org/10.1103/physrevb.78.132508

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