Optimal observables for Gaussian illumination
Su‐Yong Lee, Yonggi Jo, Taek Jeong, Jung-Hyun Kim, Dong Hwan Kim, Dongkyu Kim, Duk Y. Kim, Yong Sup Ihn, Zaeill Kim · arXiv (Cornell University) · 2021
We propose optimal observables for Gaussian illumination to maximize the signal-to-noise ratio, which minimizes the discrimination error between the presence and absence of a low-reflectivity target using Gaussian states. The optimal observables dominantly consist of off-diagonal components of output states, which is implemented with feasible setups. In the quantum regime using a two-mode squeezed vacuum state, the receiver implemented with heterodyne detections outperforms the other feasible receivers, which asymptotically improves the error probability exponent by a factor of two over the classical state bound. In the classical regime using coherent or thermal states, the receiver implemented with photon number difference measurement asymptotically approaches its bound.