2020/07/31 by S. L. Todaro, V. B. Verma, K. C. McCormick +7 · 2 citations
Physics and Astronomy · #quant-ph #cond-mat.supr-con #physics.atom-ph
paper · pdf · doi:10.1103/physrevlett.126.010501
published as Phys. Rev. Lett. 126, 010501 (2021) · 15 pages, 11 figures, including supplemental material
arxiv created 2020/07/31 · arxiv updated 2021/01/13
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 9Be+ 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 μs, 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.