Path-Symmetric States and Parity Detection in Quantum Optical Interferometry
Kaushik Parasuram Seshadreesan, Sejong Kim, Bhaskar Roy Bardhan, Jonathan P. Dowling, Hwang Lee · The Rochester Conferences on Coherence and Quantum Optics and the Quantum Information and Measurement meeting · 2013
In optical phase estimation, pure states that achieve maximal phase sensitivities with number counting, are symmetric with respect to a certain exchange of paths. We prove the optimality of photon-number parity detection for such path-symmetric states.