Single-photon-added coherent states: estimation of parameters and fidelity of the optical homodyne detection

Zavatta A., Viciani S., Bellini M.

Sergey N. Filippov, Vladimir I. Man’ko, A S Coelho +2 more

The travelling modes of single-photon-added coherent states (SPACS) are characterized by using optical homodyne tomography. Given a set of experimentally measured quadrature distributions, we estimate parameters of the state and also extract information about the detector efficiency. The method used is minimal distance estimation between theoretical and experimental quantities, which additionally allows to evaluate the precision of the estimated parameters. Given the experimental data, we also estimate the lower and upper bounds on fidelity. The results are believed to encourage a more precise engineering and detection of SPACS.

Myung Shik Kim, Kang Soo Lee, Barry C. Sanders

Ya. A. Korennoy, Vladimir I. Man’ko

Explicit expressions for optical tomograms of photon-added coherent states, even and odd photon-added coherent states, and photon-added thermal states are given in terms of Hermite polynomials. Suggestions for experimental homodyne detection of the considered photon states are presented.

Changhun Oh, Su-Yong Lee, Hyunchul Nha +1 more

We study the sensitivity of phase estimation in a lossy Mach-Zehnder interferometer (MZI) using two general, and practical, resources generated by a laser and a nonlinear optical medium with passive optimal elements, which are readily available in the laboratory: One is a two-mode separable coherent and squeezed vacuum state at a beam splitter and the other is a two-mode squeezed vacuum state. In view of the ultimate precision given by quantum Fisher information, we show that the two-mode squeezed vacuum state can achieve a lower bound of estimation error than the coherent and squeezed vacuum state under a photon-loss channel. We further consider practical measurement schemes, homodyne detection and photon number resolving detection (PNRD), to characterize the accuracy of phase estimation in reality and find that the coherent and squeezed vacuum state largely achieves a lower bound than the two-mode squeezed vacuum in the lossy MZI while maintaining quantum enhancement over the shot-noise limit. By comparing homodyne detection and PNRD, we demonstrate that quadrature measurement with homodyne detection is more robust against photon loss than parity measurement with PNRD. We also show that double homodyne detection can provide a better tool for phase estimation than single homodyne detection against photon loss.

Z. Y. Ou