The ²F_7/2 state in ¹⁷¹Yb⁺ as a resource for high SPAM fidelity

The unique metastable ²F_7/2 state in ¹⁷¹Yb⁺ is a powerful tool for achieving low state preparation and measurement (SPAM) errors in trapped ion qubits. Narrow-band optical pumping from one of the ground-state hyperfine qubit levels to the ²F_7/2 manifold allows SPAM of ¹⁷¹Yb⁺ qubits at state of the art fidelity. As this scheme is based on frequency-selective optical pumping, it is simple to implement and does not require exceptionally fine laser control. Within the ²F_7/2 state in ¹⁷¹Yb⁺, we also implement a metastable qubit on the zero-field clock transition between the F=4 and F=3 sublevels. This "m-type" qubit features separate dissipative channels to out-couple population from either qubit state to the ground state on demand. This allows null-measurement-driven and null-measurement-certified gates in the metastable qubit, which can be used to achieve perform and validate calculations in the presence of noise.