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Influence of pump coherence on the generation of position-momentum entanglement in optical parametric down-conversion

Research output: Contribution to journalArticleScientificpeer-review


Original languageEnglish
Pages (from-to)20745-20753
Number of pages9
JournalOptics Express
Issue number15
Publication statusPublished - 22 Jul 2019
Publication typeA1 Journal article-refereed


We examine experimentally how the degree of position-momentum entanglement of photon pairs depends on the transverse coherence of the pump beam that excites them in a process of spontaneous parametric down-conversion. Using spatially incoherent light from a light-emitting diode, we obtain strong position correlation of the photons, but we find that transverse momentum correlation, and thus entanglement, is entirely absent. When we continuously vary the degree of spatial coherence on the pump beam, we observe the emergence of stronger momentum correlations and entanglement. We present theoretical arguments that explain our experimental results. Our results shed light on entanglement generation and can be applied to control entanglement for quantum information applications.

Publication forum classification

Field of science, Statistics Finland