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arXiv · 0811.2038

Spectral Effects of Strong Chi-2 Non-Linearity for Quantum Processing

P. M. Leung·William J. Munro·Kae Nemoto·T. C. Ralph
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Abstract

Optical $χ^{(2)}$ non-linearity can be used for parametric amplification and producing down-converted entangled photon pairs that have broad applications. It is known that weak non-linear media exhibit dispersion and produce a frequency response. It is therefore of interest to know how spectral effects of a strong $χ^{(2)}$ crystal affect the performance. Here we model the spectral effects of the dispersion of a strong $χ^{(2)}$ crystal and illustrate how this affects its ability to perform Bell measurements and influence the performance of a quantum gates that employ such a Bell measurement. We show that a Dyson series expansion of the unitary operator is necessary in general, leading to unwanted spectral entanglement. We identify a limiting situation employing periodic poling, in which a Taylor series expansion is a good approximation and this entanglement can be removed.

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P. M. Leung, William J. Munro, Kae Nemoto, T. C. Ralph. 2008-11-14. Spectral Effects of Strong Chi-2 Non-Linearity for Quantum Processing. https://doi.org/10.1103/physreva.79.042307

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