Precision Measurement of Lifetime and Branching Ratios of the 4f¹³(²F^o_5/2) 5d6s(¹D)¹[5/2]_5/2 state in atomic 172Yb+ ions.

Trapped ions offer a pristine platform for quantum simulation and computation using hyperfine, optical, and metastable qubits. Yb+ ions have a complex atomic structure due to transitions involving electrons from the f orbital closed inner shell. This allows for the existence of highly excited states that can be useful for repumping, detection, and state preparation in the metastable qubit encoded in the (2D3/2, 2D5/2) and (2F7/2) states. Here, we report spectroscopic and time-resolved data to characterize the atomic state . We access this state starting from the metastable (2D3/2, 2D5/2) manifold, and observe an unexpectedly long lifetime of τ = 38.0(9) µs that allows visible Rabi oscillations and sideband resolved spectroscopy. Using a combination of heralded state preparation, coherent population dynamics and optical pumping methods, we measure the branching ratios to the 2D3/2 and 2D5/2 states to be 0.363(2) and 0.637(2), respectively. We use the same methods to place an upper bound of 0.0005(2) on the branching ratio to the 2F7/2 state. Our measurements pave the way to a better understanding of the atomic structure of Yb+ ions, which still lacks accurate numerical methods, and the use of high-lying excited states for partial detection and other qubit manipulations in the omg architecture.