The ability to filter quantum states is a key capability in quantum information science and technology, in which one-qubit filters, or polarizers, have found wide application. Filtering on the basis of entanglement requires extension to multi-qubit filters with qubit-qubit interactions. We demonstrated an optical entanglement filter that passes a pair of photons if they have the desired correlations of their polarization. Such devices have many important applications to quantum technologies.
@article{arxiv.0905.0074,
title = {An Entanglement Filter},
author = {Ryo Okamoto and Jeremy L. O'Brien and Holger F. Hofmann and Tomohisa Nagata and Keiji Sasaki and Shigeki Takeuchi},
journal= {arXiv preprint arXiv:0905.0074},
year = {2009}
}