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High-contrast dispersive readout of a superconducting flux qubit using a nonlinear resonator

A. Lupascu·E. F. C. Driessen·L. Roschier·C. J. P. M. Harmans·J. E. Mooij
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Abstract

We demonstrate high-contrast state detection of a superconducting flux qubit. Detection is realized by probing the microwave transmission of a nonlinear resonator, based on a SQUID. Depending on the driving strength of the resonator, the detector can be operated in the monostable or the bistable mode. The bistable operation combines high-sensitivity with intrinsic latching. The measured contrast of Rabi oscillations is as high as 87 %; of the missing 13 %, only 3 % is unaccounted for. Experiments involving two consecutive detection pulses are consistent with preparation of the qubit state by the first measurement.

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A. Lupascu, E. F. C. Driessen, L. Roschier, C. J. P. M. Harmans, J. E. Mooij. 2006-01-27. High-contrast dispersive readout of a superconducting flux qubit using a nonlinear resonator. https://doi.org/10.1103/physrevlett.96.127003

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