By Zanforlin U., Lupo C., Connolly P.W.R., Kok P., Buller G.S., Huang Z.
Submitted to arXiv on 22 February 2022.
Estimating the angular separation between two incoherent thermal sources is a challenging task for direct imaging, especially when it is smaller than or comparable to the Rayleigh length. In addition, the task of discriminating whether there are one or two sources followed by detecting the
faint emission of a secondary source in the proximity of a much brighter one is in itself a severe challenge for direct imaging. Here, we experimentally demonstrate two tasks for super resolution imaging based on quantum state discrimination and quantum imaging techniques. We show that
one can significantly reduce the probability of error for detecting the presence of a weak secondary source, especially when the two sources have small angular separations. In this work, we reduce the experimental complexity down to a single two-mode interferometer: we show that (1) this simple
set-up is sufficient for the state discrimination task, and (2) if the two sources are of equal brightness, then this measurement can super-resolve their angular separation, saturating the quantum Cram´erRao bound. By using a collection baseline of 5.3 mm, we resolve the angular separation of two
sources that are placed 15 µm apart at a distance of 1.0 m with an accuracy of 1.7%–this is between 2 to 3 orders of magnitudes more accurate than shot-noise limited direct imaging.