Scalable hyperfine qubit state detection via electron shelving in the 2D5/2 and 2F7

Abstract

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 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 Yb + and achieve a 5.6× reduction in single-ion detection error on an avalanche photodiode to 1.8(2) × 10 −3 in a 100 μs detection period and a 4.3× error reduction on an electron multiplying CCD camera with 7.7(2) × 10 −3 error in 400 μs. 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× and 12× reductions in error to 6(7) × 10 −6 and 6.3(3) × 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 ultrahighfidelity detection in 171 Yb + .

Precision characterization of the D5/22 state and the quadratic Zeeman coefficient in Yb+17

“…Furthermore, these results provide the necessary characterizations required for improving the measurement fidelity of 171 Yb + hyperfine qubits, as detailed in our separate manuscript Ref. [29].…”

“…Furthermore, the metastable 2 D levels in 171 Yb + provide extra degrees of freedom for applications in QIP. These find use in [28] or to scalably improve qubit measurement fidelities with minimal technical overhead [29].…”

Probing finite-temperature observables in quantum simulators with short-time dynamics

“…The phase ϕ can be obtained from a Ramsey-type experiment by interfering a state which evolves under Ĥ with one that does not. To engineer such a state, we introduce a shelving state |s which does not couple to the qubit levels under Ĥ, such as one of the D 5/2 Zeeman sublevels in 40 Ca + [35] or the 2 D 5/2 state in 171 Yb + [36]. This allows us to obtain the phase ϕ by rotating into a superposition between |ψ and |s • • • s , evolving it in time, rotating back and measuring the return probability to |ψ (see supplement and Ref.…”

Precision Characterization of the $^2$D$_{5/2}$ State and Quadratic Zeeman Coefficient in $^{171}$Yb$^+$

“…These results can be used to benchmark and verify quantum many-body calculations and provide the necessary characterizations for improving measurement fidelity of 171 Yb + qubits as detailed in Ref. [29].…”

“…In addition to testing fundamental physics and providing benchmarks for atomic calculations, the metastable 2 D levels in 171 Yb + provide extra degrees of freedom for applications in QIP. These find use in implementing entangling gate operations [28] or to scalably improving qubit measurement fidelities with minimal technical overhead [29].…”