Nonclassical Measure of Multi-mode Radiation Field

Kisik Kim

F. T. Arecchi, Maria Asdente, A.M. Ricca

Jan Sperling, W. Vogel, G. S. Agarwal

We present a general method to detect nonclassical radiation fields with systems of on-off detectors. We especially study higher order correlations for the identification of nonclassical radiation. This allows us to directly characterize quantum correlations by the statistics measured with systems of on-off detectors. Additionally, we generalize our method to multiple detector systems for measurements of correlations between light fields. We also consider multimode radiation fields and isolate nonclassicality in terms of the space time correlations. Finally, we present results for the quantum statistics using on-off detectors operating in nonlinear detection modes.

Young‐Chul Kim, Jaewoo Noh, Kisik Kim

Ivan Gonoskov, Christian Hünecke, Stefanie Gräfe

We present an analytical framework for the emergence of nonclassical radiation in strongly laser-driven quantum systems, with a focus on high-order harmonic generation (HHG). Starting from a Pauli-Fierz description, we employ a parametric factorization of the coupled light-matter wavefunction that reduces the dynamics to coupled equations for a field-driven electronic state and a quantized light mode. Within this framework, we identify a simple and predictive mechanism for nonclassicality: it originates from the nonlinear dependence of the electronic dipole response on the light-mode coordinate. An approximately constant dipole yields coherent radiation, a linear dependence produces squeezing, and higher-order nonlinearities give rise to Wigner-function negativity. We illustrate this mechanism for atomic and molecular model systems and analyze its scaling in multi-emitter configurations, indicating routes toward high-photon-number nonclassical radiation in HHG. Our results provide a transparent connection between strong-field dynamics and quantum-optical properties of emitted light, offering a basis for engineering nonclassical states in intense laser-matter interactions.

Kisik Kim

We generate multi-mode nonclassical correlations in the output field from the single-mode nonclassicality in the input field with a unitary optical device. It is shown that, according to the invariance of nonclassicality, the decrement of the single-mode nonclassicality is compensated for by the appearance of multi-mode nonclassical correlations. We demonstrate a complete transfer of single-mode nonclassicality to a multi-mode nonclassical correlation for a 1 × 2 array of beam splitters, when chaotic lights are taken as auxiliary classical fields of the input.