Table 1 Experimental error budget for state preparation and measurement (SPAM) of the 133Ba+ hyperfine qubit.

From: High-fidelity manipulation of a qubit enabled by a manufactured nucleus

Process

Average error ×10−4

Initialization to \(\left|0\right\rangle\)

0.1

Off-resonant shelving \(\left|0\right\rangle\)

1.0

Readout of 2S1/2 manifold

0.1

\(\left|0\right\rangle\) → \(\left|1\right\rangle\) CP Robust 180 sequence

0.5

Shelving \(\left|1\right\rangle\)

1.0

Spontaneous decay during readout

0.7

Total average SPAM error

3.4

  1. Errors are estimates based on theoretical models and auxiliary experiments. The \(\left|0\right\rangle\) state SPAM is limited by off-resonant scatter from the laser used for electron shelving. The \(\left|1\right\rangle\) state electron shelving is limited by the 2P3/2 hyperfine splitting, where off-resonant scatter can cause spontaneous emission to the \(\left|0\right\rangle\) state. Spontaneous emission of the 2D5/2 state and preparation of the \(\left|1\right\rangle\) state via microwaves are the next largest contribution to the \(\left|1\right\rangle\) state SPAM error.
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