Quality of spatial entanglement propagation

Matthew Reichert, Xiaohang Sun, Jason W. Fleischer

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


We explore, both experimentally and theoretically, the propagation dynamics of spatially entangled photon pairs (biphotons). Characterization of entanglement is done via the Schmidt number, which is a universal measurement of the degree of entanglement directly related to the nonseparability of the state into its subsystems. We develop expressions for the terms of the Schmidt number that depend on the amplitude and phase of the commonly used double-Gaussian approximation for the biphoton wave function, and demonstrate migration of entanglement between amplitude and phase upon propagation. We then extend this analysis to incorporate both phase curvature in the pump beam and higher spatial frequency content of more realistic non-Gaussian wave functions. Specifically, we generalize the classical beam quality parameter M2 to the biphotons, allowing the description of more information-rich beams and more complex dynamics. Agreement is found with experimental measurements using direct imaging and Fourier optics.

Original languageEnglish (US)
Article number063836
JournalPhysical Review A
Issue number6
StatePublished - Jun 22 2017

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


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