2003/10/28 by Hugues De Riedmatten, Hugues de Riedmatten, Valerio Scarani +6 · 2 citations
Computer Science · Physics and Astronomy · #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum optics and atomic interactions #quant-ph
paper · pdf · doi:10.1080/09500340408232478
published as J.Mod.Opt. 51, 1637 (2004) · 10 pages, 3 figures, submitted
arxiv created 2003/10/28 · openalex publication_date 2004/07/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/29
We study the physics of four-photon states generated in spontaneous parametric down-conversion with a pulsed pump field. In the limit where the coherence time of the photons t ph c is much shorter than the duration of the pump pulse Δt, the four photons can be described as two independent pairs. In the opposite limit, the four photons are in a four-particle entangled state. Any intermediate case can be characterized by a single parameter χ, which is a function of t ph c Δt. We present a direct measurement of χ through a simple experimental set-up. The full theoretical analysis is also provided.