Qubits encoded in hyperfine states of trapped ions are ideal for quantum computation given their long lifetimes and low sensitivity to magnetic fields, yet they suffer from off-resonant scattering during detection, often limiting their measurement fidelity. In ${}^{171}{\text{Yb}}^{+}$ this is exacerbated by a low fluorescence yield, which leads to a need for complex and expensive hardware, a problematic bottleneck especially when scaling up the number of qubits. We demonstrate a detection routine based on electron shelving to address this issue in ${}^{171}{\text{Yb}}^{+}$ and achieve a $5.6\times$ reduction in single-ion detection error on an avalanche photodiode to $1.8\left(2\right)\times {10}^{-3}$ in a 100 $\mu \mathrm{s}$ detection period and a $4.3\times$ error reduction on an electron multiplying CCD camera with $7.7\left(2\right)\times {10}^{-3}$ error in 400 $\mu \mathrm{s}$. We further improve the characterization of a repump transition at 760 nm to enable a more rapid reset of the auxiliary ${}^2{F}_{7/2}$ states populated after shelving. Finally, we examine the detection fidelity limit using the long-lived ${}^2{F}_{7/2}$ state, achieving further $300\times$ and $12\times$ reductions in error to $6\left(7\right)\times {10}^{-6}$ and $6.3\left(3\right)\times {10}^{-4}$ in 1 ms on the respective detectors. While shelving-rate limited in our setup, we suggest various techniques to realize this detection method at speeds compatible with quantum information processing, providing a pathway to ultrahigh-fidelity detection in ${}^{171}{\text{Yb}}^{+}$.

• Received 29 December 2020
• Accepted 9 June 2021

DOI:https://doi.org/10.1103/PhysRevA.104.012606