Fig. 2
From: Programmable four-photon graph states on a silicon chip
Summary of experimental data. a, b Stabiliser observables of the star and line graph states, 〈S4|gi|S4〉 and 〈L4|gi|L4〉, used to estimate state fidelity. Dashed lines indicate the F > 1/2 threshold to witness genuine multipartite entanglement, where F = mean{〈gi〉}. The final bar of each plot, gigi, is the identity for any i ∈ {1, 2, 3, 4}. c Mermin parameters \({\mathscr{M}}_{II}^G\) and \({\mathscr{M}}_{III}^G\) for the |S4〉 and |L4〉 states, estimated from stabilisers measurements. Local hidden variable bounds are indicated with a dashed line. Values are reported in Table 1. d On-chip Hong-Ou-Mandel interference, with HOM fringe visibility of V = 0.82 ± 0.02. Probability distributions for the e indistinguishability, f source brightness, and g phase error, derived via a Bayesian parameter estimation method. All error bars represent the standard error of the mean, obtained from Monte Carlo simulations assuming a Poissonian distribution of the measured counts
