Fig. 3: Average phase sensing results. | npj Quantum Information

Fig. 3: Average phase sensing results.

From: A variational toolbox for quantum multi-parameter estimation

Fig. 3

Semi-logarithmic plot of the Cramér-Rao bound for average phase sensing over the dephasing probability of (blue) the standard Ramsey probe and (orange) a GHZ probe. Each green dot marks the bound for a probe optimized for the particular dephasing probability. The phase shifts were fixed at the optimal spot for GHZ sensing at \({\upphi }_{j}=\frac{\pi }{6}\). We recover the optimality of the GHZ probe in the noiseless case and find improved sensing protocols in the noisy case.

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