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Journal of the Optical Society of America B

On the control of the momentum distribution of paired photons generated by non-collinear type-II spontaneous parametric down-conversion

Omar Calderón-Losada, Alejandra Valencia

Published Jun 7, 2019• 0 citations
Publisher

Abstract

We present a theoretical and experimental characterization of the joint spatial distribution of paired photons generated via non-collinear type-II spontaneous parametric down-conversion. Specifically, for the photons created parallel and perpendicular to the optical table, we determine the shape of such distributions and the degree of correlation of these photons. The characterization is done for different sizes of the pump beam waist. We found that it is possible to have different spatial distributions of the photons with the same degree of correlation.

DOI
10.1364/josab.36.001769

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We present a theoretical and experimental characterization of the joint spatial distribution of paired photons generated via non-collinear type-II spontaneous parametric down-conversion. Specifically, for the photons created parallel and perpendicular to the optical table, we determine the shape of such distributions and the degree of correlation of these photons. The characterization is done for different sizes of the pump beam waist. We found that it is possible to have different spatial distributions of the photons with the same degree of correlation.
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We report a theoretical study of spatial and spectral profiles of twin photons generated with a pump beam having a partially spatially coherent nature. These profiles are simulated for both type-I and type-II spontaneous parametric down conversion in collinear and non-collinear configurations and found to be highly dependent on the choice of beam waist and transverse correlation length of the pump beam. It is found that by suitable selection of coherence length and size of the pump beam, the asymmetry in spatial geometry of down-converted photons and the spectral width can be modified. Owing to the partially spatially coherent nature, these biphoton beams might offer more robustness against losses compared to their fully coherent counterparts, and thus could yield a high success rate in free-space quantum communication and in quantum key distribution.
The ability to engineer the properties of quantum optical states is essential for quantum information processing applications. Here, we demonstrate tunable control of spatial correlations between photon pairs produced by spontaneous parametric down-conversion. By shaping the spatial pump beam profile in a type-I collinear configuration, we tailor the spatial structure of coincidences between photon pairs entangled in high dimensions, without effect on intensity. The results highlight fundamental aspects of spatial coherence and hold potential for the development of quantum technologies based on high-dimensional spatial entanglement.