Large-baseline quantum telescopes assisted by partially distinguishable photons

Quantum entanglement can be used to extend the baseline of telescope arrays in order to increase the spatial resolution. In one proposal by Marchese and Kok [Phys. Rev. Lett. 130, 160801 (2023)], identical single photons are shared between receivers and interfere with a star photon. In this paper we consider two outstanding questions: (i) what is the precise effect of the low photon occupancy of the mode associated with the starlight? and (ii) what is the effect on the achievable resolution of imperfect indistinguishability (or partial distinguishability) between the ground and star photons? We find that the effect of distinguishability is relatively mild, but low photon occupancy of the optical mode of the starlight quickly deteriorates the sensitivity of the telescope for higher auxiliary photon numbers.