Scalable hyperfine qubit state detection via electron shelving in the ${}^2$D$_{5/2}$ and ${}^2$F$_{7/2}$ manifolds in ${}^{171}$Yb$^{+}$

Realizing coherently convertible dual-type qubits with the same ion species

“…For a single S-qubit, we achieve 98.3% fidelity for detection using 370 nm laser and 99.98% fidelity for single-qubit rotations via 12.6 GHz microwave, which suffice for our experiment. If higher detection fidelity is needed, we can apply the electron shelving technique [21][22][23] and have gotten a detection fidelity above 99.9% in our experiment. More details can be found in Methods.…”

“…In our experiment, the F-qubit is detected by electron shelving as shown in the main text with a detection fidelity of (99.86±0.03)% at 0.25 ms detection time, which can be further improved to (99.97±0.004%) at 2.5 ms detection time. The S-qubit can be detected by the routine 370 nm laser with a detection fidelity of (98.3 ± 0.2)%, or by the electron shelving method 22 with a detection fidelity of (99.91 ± 0.007)%.…”

“…We then demonstrate that, during the operations on one qubit type such as cooling, gates and detection, the coherence of the other qubit type is well preserved with the crosstalk error rate below 0.03% per operation. Note that the transition to the meta-stable D or F levels have been used before in ion trap experiments for qubit detection through electron shelving [21][22][23] and for temporary protection of the optical qubits under detection 24,25 . The contribution here is that we achieve the first fast coherent conversion between dual types of…”