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arXiv · 2506.06460

Direct Polarization-Entangled Photon Pair Generation Using Domain-Engineered Nonlinear Crystals

Anatoly Shukhin·Inbar Hurvitz·Leonid Vidro·Ady Arie·Hagai S. Eisenberg
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Abstract

A bi-photon polarization-frequency entanglement source was realized by shaping the phase-matching function of a poled KTP crystal. It provides a simple method to achieve either polarization or spectral entanglement in a simple collinear setup, based on single-pass SPDC and a dichroic (or polarizing) beam splitter. This is a robust and cost-effective configuration that can be easily implemented outside the laboratory environment. We characterized the source by two approaches: reconstructing the density matrix of the generated state with quantum state tomography, by recording the coincidences across 16 mutual polarization settings, in addition to a new method based on quantifying the symmetry of the joint spectral intensity by swapping between the signal and idler wavelengths. The polarization-entangled source violates the Clauser-Horne-Shimony-Holt inequality with a measured $S=2.747\pm 0.004$. We also measured the polarization entanglement visibility in two mutually unbiased polarization bases and evaluated the squeezing level by characterizing the reduction in visibility at high pump power.

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Anatoly Shukhin, Inbar Hurvitz, Leonid Vidro, Ady Arie, Hagai S. Eisenberg. 2025-06-06. Direct Polarization-Entangled Photon Pair Generation Using Domain-Engineered Nonlinear Crystals. https://arxiv.org/abs/2506.06460

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