Exploiting separation-dependent coherence to boost optical resolution

The problem of resolving pointlike light sources not only serves as a benchmark for optical resolution but also holds various practical applications ranging from microscopy to astronomy. In this paper, we aim to resolve two thermal sources sharing arbitrary mutual coherence using the spatial mode demultiplexing technique. Our analytical study includes scenarios where the coherence and the emission rate depend on the separation between the sources, and is not limited to the faint sources limit. We consider the fluorescence of two interacting dipoles to demonstrate that the dependence of emission characteristics on the parameter of interest can boost the sensitivity of the estimation and noticeably prolong the duration of information decay.