Optimized phase detection

Yanchun Yin, Igor Jovanovic

Jun Xin, Xiao-Ming Lu, Xingmin Li +1 more

Optimal phase point, where the best phase sensitivity can be achieved, plays an important role in the operation of an interferometer. In this paper, we theoretically investigate the optimal phase point of an SU(1,1) interferometer in joint intensity detection and joint homodyne detection, respectively. We demonstrate that for joint intensity detection, the optimal phase point of the SU(1,1) interferometer happens nearby the dark fringe with realistic factors considered. The divergence of the optimal phase point from the dark fringe can be dependent on the initial injection scheme of the SU(1,1) interferometer, the strength of the parametric amplifier inside the interferometer, and the internal losses of the system. In addition, we find that for joint homodyne detection, the optimal phase point of the SU(1,1) interferometer can happen only at the bright or dark fringe. Our results may pave the way to real applications of the SU(1,1) interferometer.

Alexander Steingaß

Weng-Long Chang, Athanasios V. Vasilakos

Marco G. Genoni, Stefano Olivares, Matteo G. A. Paris

The measurement problem for the optical phase has been traditionally attacked for noiseless schemes or in the presence of amplitude or detection noise. Here we address the estimation of phase in the presence of phase diffusion and evaluate the ultimate quantum limits to precision for phase-shifted Gaussian states. We look for the optimal detection scheme and derive approximate scaling laws for the quantum Fisher information and the optimal squeezing fraction in terms of the total energy and the amount of noise. We also find that homodyne detection is a nearly optimal detection scheme in the limit of very small and large noise.

Chiara Macchiavello

We study the issue of simultaneous estimation of several phase shifts induced by commuting operators on a quantum state. We derive the optimal positive-operator-valued measure corresponding to the multiple-phase estimation. In particular, we discuss the explicit case of the optimal detection of double phase for a system of identical qutrits and generalize these results to optimal multiple-phase detection for d-dimensional quantum states.