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Is orbital angular momentum always conserved in spontaneous parametric down-conversion?

Sheng Feng·Chao-Hsiang Chen·Geraldo A. Barbosa·Prem Kumar
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Abstract

In the non-linear optical process of type-II spontaneous parametric down-conversion, we present on an experiment showing that the two-photon detection amplitude of the down-converted beams does not generally reproduce the transverse profile of the pump beam that carries non-zero orbital angular momentum. We explain this observation by that orbital angular momentum is not conserved in the type-II non-linear process due to the broken rotational symmetry of the Hamiltonian.

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Sheng Feng, Chao-Hsiang Chen, Geraldo A. Barbosa, Prem Kumar. 2007-04-20. Is orbital angular momentum always conserved in spontaneous parametric down-conversion?. https://doi.org/10.1117/12.734118

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