Genuine Multipartite Entanglement in the 3-Photon Decay of Positronium

Beatrix C. Hiesmayr, Pawel Moskal
2017 Scientific Reports  
The electron-positron annihilation into two photons is a standard technology in medicine to observe e.g. metabolic processes in human bodies. A new tomograph will provide the possibility to observe not only direct e^+ e^- annihilations but also the 3 photons from the decay of ortho-positronium atoms formed in the body. We show in this contribution that the three-photon state with respect to polarisation degrees of freedom depends on the angles between the photons and exhibits various specific
more » ... tanglement features. In particular genuine multipartite entanglement, a type of entanglement involving all degrees of freedoms, is subsistent if the positronium was in a definite spin eigenstate. Remarkably, when all spin eigenstates are mixed equally, entanglement --and even stronger genuine multipartite entanglement-- survives. Due to a "symmetrization" process, however, Dicke-type of entanglement remains whereas GHZ-type of entanglement vanishes. The survival of particular entanglement properties in the mixing scenario may make it possible to extract quantum information in form of distinct entanglement features, e.g., from metabolic processes in human bodies.
doi:10.1038/s41598-017-15356-y pmid:29127376 pmcid:PMC5681662 fatcat:ew7hyjawmrhxbgbe267f7caoiu