Quantum Fisher information for estimating N partially coherent point sources

Abstract

A partially coherent object’s localization parameters are shown to be theoretically estimable with higher precision than those of an incoherent object, and the maximum number of independent parameters that have non-vanishing precision in the sub-Rayleigh regime is 3 (compared to 2 for an incoherent object). Normalization schemes, which are crucial in the proper interpretation of quantum Fisher information results in the presence of partial coherence, are introduced and detailed.