Figure 9

(a) Quantum circuit that prepares \(| \Psi (\theta ) \rangle \). (b) Expectation value of the CHSH observable Eq. (6) in the state \(| \Psi (\theta ) \rangle \), plotted over the y rotation angle θ. The raw experimental data points are shown with blue dots; the implementation of readout error mitigation (green crosses) brings them closer to the ideal noiseless result (red curve). There are two regions outside the black horizontal lines, where the CHSH inequality is violated and hence non-locality is demonstrated. The statistical uncertainty is so small that the error bars remain within the markers