Injecting a non-Gaussian (Fock or Shr\"odinger cat) quantum state into the dark port of a two-arm interferometer and a strong classical light into the bright one, it is possible, in principle, to detect a given phase shift unambiguously using the orthogonality between the original and displaced in the interferometer non-Gaussian states. The optical losses degrade the sensitivity, introducing the finite "false positive" and "false negative" detection errors. However, using the state-of-art photodetectors, it is still possible to obtain better detection fidelity than in the case of Gaussian quantum states.
@article{arxiv.2405.07049,
title = {Using non-Gaussian quantum states for detection of a given phase shift},
author = {V. L. Gorshenin and F. Ya. Khalili},
journal= {arXiv preprint arXiv:2405.07049},
year = {2024}
}