arXiv:1809.04830 · Optics Express
Super-resolved angular displacement estimation based upon a Sagnac interferometer and parity measurement
Jiandong Zhang, Zijing Zhang, Longzhu Cen, Jun-Yan Hu, Yuan Zhe Zhao
Abstract
Super-resolved angular displacement estimation is of crucial significance to the field of quantum information processing. Here we report an estimation protocol based on a Sagnac interferometer fed by a coherent state carrying orbital angular momentum. In a lossless scenario, through the use of parity measurement, our protocol can achieve a 4ℓ-fold super-resolved output with quantum number ℓ; meanwhile, a shot-noise-limited sensitivity saturating the quantum Cramér-Rao bound is reachable. We also consider the effects of several realistic factors, including nonideal state preparation, photon loss, and inefficient measurement. Finally, with mean photon number N ¯ = 2.297 and ℓ = 1 taken, we experimentally demonstrate a super-resolved effect of angular displacement with a factor of 7.88.