2011/06/28 by K. Dechoum, W. S. Marques, A. Z. Khoury
Computer Science · Physics and Astronomy · #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum optics and atomic interactions #quant-ph
paper · pdf · doi:10.1103/physreva.83.063843
published as Physical Review A 83, 063843 (2011) · 4 pages, 2 figures
openalex publication_date 2011/06/28 · arxiv created 2011/07/13 · arxiv updated 2011/07/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We analyze the three-mode correlation properties of the electromagnetic field in a optical parametric oscillator below-threshold. We employ a perturbative expansion of the It\o equations derived from the positive-P representation of the density matrix. Using the generalized Cauchy-Schwarz inequality, we investigate the genuine quantum nature of the triple correlations between the interacting fields, since in this case continuous-variable entanglement is not detected by the van Loock-Furusawa criterion [Phys. Rev. A 67, 052315 (2003)]. Although not being a necessary condition, these triple correlations are sufficient evidence of tripartite entanglement. Of course, our characterization of the quantum correlations is applicable to non-Gaussian states, which we show to be the case of the optical parametric oscillator below-threshold, provided nonlinear quantum fluctuations are properly taken into account.