Characterization of Generalized Coherent States through Intensity-Field Correlations

TL;DR

This paper shows that intensity-field correlation measurements can effectively detect nonclassicality in generalized coherent states, which are important for quantum technologies, offering a practical and simple experimental method.

Contribution

It introduces a straightforward intensity-field correlation approach to identify nonclassicality in GCSs, extending analysis to Kerr states and mixtures.

Findings

Normalized correlation deviates from unity for nonclassical GCSs.

Analytical results derived for Kerr-generated states.

Method enables real-time detection of quantum features.

Abstract

Non-Gaussian quantum states of light are essential resources for quantum information processing and precision metrology. Among them, generalized coherent states (GCS), which naturally arise from the evolution of a coherent state with a nonlinear medium, exhibit useful quantum features such as Wigner negativity and metrological advantages [Phys. Rev. Res. 5, 013165 (2023)]. Because these states remain coherent to all orders, their nonclassical character cannot be revealed through standard intensity-intensity correlation measurements. Here, we demonstrate that the intensity-field correlation function alone provides a simple and experimentally accessible witness of nonclassicality. For GCSs, any deviation of this normalized correlation from unity signals nonclassical behavior. We derive analytical results for Kerr-generated states and extend the analysis to statistical mixtures of GCSs. The proposed approach enables real-time, low-complexity detection of quantum signatures in non-Gaussian states, offering a practical tool for experiments across a broad range of nonlinear regimes.