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arXiv · 2008.00065

State Readout of a Trapped Ion Qubit Using a Trap-Integrated Superconducting Photon Detector

S. L. Todaro·V. B. Verma·K. C. McCormick·D. T. C. Allcock·R. P. Mirin·D. J. Wineland·S. W. Nam·A. C. Wilson·D. Leibfried·D. H. Slichter
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Abstract

We report high-fidelity state readout of a trapped ion qubit using a trap-integrated photon detector. We determine the hyperfine qubit state of a single $^9$Be$^+$ ion held in a surface-electrode rf ion trap by counting state-dependent ion fluorescence photons with a superconducting nanowire single-photon detector (SNSPD) fabricated into the trap structure. The average readout fidelity is 0.9991(1), with a mean readout duration of 46 $\mu$s, and is limited by the polarization impurity of the readout laser beam and by off-resonant optical pumping. Because there are no intervening optical elements between the ion and the detector, we can use the ion fluorescence as a self-calibrated photon source to determine the detector quantum efficiency and its dependence on photon incidence angle and polarization.

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S. L. Todaro, V. B. Verma, K. C. McCormick, D. T. C. Allcock, R. P. Mirin, D. J. Wineland, S. W. Nam, A. C. Wilson, D. Leibfried, D. H. Slichter. 2020-07-31. State Readout of a Trapped Ion Qubit Using a Trap-Integrated Superconducting Photon Detector. https://doi.org/10.1103/physrevlett.126.010501

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