Phase estimation in lossy optical interferometry without a reference beam
Jun Tang, Dongqing Wang, Wei Zhong, Lan Zhang Zhou, Yu‐Bo Sheng · Communications in Theoretical Physics · 2025
Abstract We investigate phase estimation in a lossy interferometer using entangled coherent states, with a particular focus on a scenario where no reference beam is employed. By calculating the quantum Fisher information, we reveal two key results: (1) the metrological equivalence between scenarios with and without a reference beam, established under ideal lossless conditions for the two-phase-shifting configuration, breaks down in the presence of photon loss, and (2) the pronounced inferior performance of ECSs relative to NOON states, observed in the presence of a reference beam, disappears in its absence.