Fig. 8: Sensing the relative phase θ with a pure N-photon state, ψN, in a lossy interferometer with dark counts. | Nature Communications

Fig. 8: Sensing the relative phase θ with a pure N-photon state, ψN, in a lossy interferometer with dark counts.

From: Quantum metrology with imperfect measurements

Fig. 8

Either a global (affects all the photons) or local (affects each photon separately) control unitary is allowed. The imperfect measurement is described by an ideal photon-number detection (j, N−j) at the output modes, followed by a noisy detection channel \({{{{{{{\mathcal{P}}}}}}}}\) that incorporates losses and dark counts, resulting in (x1, x2) registered detection counts.

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