Two independent photon pairs versus four-photon entangled states in parametric down conversion
Abstract
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 tc is much shorter than the duration of the pump pulse Delta t, 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 chi, which is a function of tc/Delta t. We present a direct measurement of chi through a simple experimental setup. The full theoretical analysis is also provided.
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.