Photons may have homogeneous polarization and may carry quantized orbital angular momentum (OAM). Photon entanglement has been realized in various degrees of freedom such as polarization and OAM. Using a pair of orthogonally polarized states carrying opposite-handedness quantized OAMs could create "quantized" vector polarization states with space-variant polarization structures. It is thus possible to extend the polarization degree of freedom from two dimensional space to indefinite dimensional discrete Hilbert space. We present a class of vector-polarization entangled Bell states, which use the spatial modes of the vector fields with space-variant polarization structure. We propose a scheme of creating the vector-polarization entangled Bell states using a Sagnac interferometer. We also design an analyzer for identifying the vector-polarization entangled Bell states. Such a class of entanglement is important for quantum information science and technology, and fundamental issues of quantum theory, due to its advantage of the increase in information capacity.
@article{arxiv.1512.00599,
title = {Entanglement of Vector-Polarization States of Photons},
author = {Ling-Jun Kong and Yongnan Li and Yu Si and Rui Liu and Zhou-Xiang Wang and Chenghou Tu and Hui-Tian Wang},
journal= {arXiv preprint arXiv:1512.00599},
year = {2015}
}