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



Susanna L. Todaro, Varun Verma, Katherine C. McCormick, David T. Allcock, Richard Mirin, David J. Wineland, Sae Woo Nam, Andrew C. Wilson, Dietrich Leibfried, Daniel Slichter


We detect fluorescence photons emitted by a single $^9$Be$^+$ ion confined in a surface- electrode rf ion trap, using a superconducting nanowire single photon detector integrated directly into the trap. We achieve a qubit readout fidelity of 99.91(1) % with an average readout duration of 46 $\mu$s, limited by the polarization impurity of the readout laser beam and off-resonant optical pumping into the fluorescing state. We use the ion fluorescence to perform an absolute calibration of the detector quantum efficiency and characterize its dependence on incidence angle and polarization.
Physical Review Letters


Superconducting photon detector, single photon detector, ion trap, quantum measurement, quantum computing


Todaro, S. , Verma, V. , McCormick, K. , Allcock, D. , Mirin, R. , Wineland, D. , Nam, S. , Wilson, A. , Leibfried, D. and Slichter, D. (2021), State Readout of a Trapped Ion Qubit Using a Trap-integrated Superconducting Photon Detector, Physical Review Letters, [online], (Accessed May 29, 2024)


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Created January 6, 2021, Updated April 23, 2021