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Updated: Jun 21, 2026

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
X entanglement: the nonfactorable spatiotemporal structure of biphoton correlation
A Gatti1, E Brambilla, L Caspani
1INFM-CNR-CNISM, Dipartimento di Fisica e Matematica, Università dell'Insubria, Via Valleggio 11, 22100 Como, Italy.
Abstract:
We investigate the spatiotemporal structure of the biphoton entanglement in parametric down-conversion (PDC) and we demonstrate its nonfactorable X-shaped geometry. Such a structure gives access to the ultrabroad bandwidth of PDC, and can be exploited to achieve a biphoton temporal localization in the femtosecond range. This extreme localization is connected to our ability to resolve the photon positions in the source near field. The nonfactorability opens the possibility of tailoring the temporal entanglement by acting on the spatial degrees of freedom of twin photons.
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