Optimal quantum detection strategy for super-resolving angular-rotation measurement

Super-resolving angular-rotation measurement based on photon orbital angular momentum has recently become a research hotspot. The selection of a proper quantum detection strategy is extremely important for improved quantum-enhanced performance. Here, three types of quantum detection strategies (binary-outcome homodyne detection, parity detection and zero–nonzero photon counting) are discussed. The analytical expressions of their output signals and sensitivities are derived theoretically, and numerical calculation results indicate that parity detection is the best quantum detection strategy for super-resolving angular-rotation measurement. Finally, the impacts of photon loss on the resolution and sensitivity of the three quantum detection strategies are investigated.