Table 2 Maximum readout visibility for the four spin states of the two-qubit system.

From: Single-spin qubits in isotopically enriched silicon at low magnetic field

Spin state

Readout outcome

Visibility

Method

Limitation

\(\left|\uparrow \uparrow \right\rangle\)

Triplet

87\(\pm\)1.9%

ESR driven \(\left|\uparrow \uparrow \right\rangle \iff \left|\uparrow \downarrow \right\rangle\) oscillation

Control

\(\left|\downarrow \uparrow \right\rangle\)

Triplet

99.3\(\pm\)2.3%

Exchange driven \(\left|\downarrow \uparrow \right\rangle \iff \left|\uparrow \downarrow \right\rangle\) oscillation

Readout

\(\left|\uparrow \downarrow \right\rangle\)

Singlet

99.5\(\pm\)0.7%

\(\left|\uparrow \downarrow \right\rangle \Rightarrow \left|\downarrow \downarrow \right\rangle\)\({T}_{1}\) relaxation

Readout

\(\left|\downarrow \downarrow \right\rangle\)

Triplet

96.8\(\pm\)1.0%

\(\left|\uparrow \downarrow \right\rangle \Rightarrow \left|\downarrow \downarrow \right\rangle\)\({T}_{1}\) relaxation

Thermalization

  1. The error bar for \(\left|\uparrow \uparrow \right\rangle\) state visibility is derived from the fit of ESR-driven Rabi oscillations shown in Fig. 2d. Similarly, the fit of exchange-driven Rabi oscillations, discussed in Methods and shown in Supplementary Fig. 1c, gives the error bar for \(\left|\downarrow \uparrow \right\rangle\) state visibility. The exchange-driven \(\left|\downarrow \uparrow \right\rangle \iff \left|\uparrow \downarrow \right\rangle\) oscillation experiment is discussed in Methods and reported in Supplementary Fig. 1. The errors for \(\left|\uparrow \downarrow \right\rangle\) and \(\left|\downarrow \downarrow \right\rangle\) state visibility are derived from the fit of the exponential decay curve between the two states as discussed in Methods and shown in Supplementary Fig. 2. All error bars represent 95% confidence intervals derived from the uncertainties of measurement setup resolution or data fitting
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