Abstract
We demonstrate genuine multipartite quantum entanglement of four photons in their orbital angular momentum degrees of freedom, where a high-dimensional discrete Hilbert space is attached to each photon. This can encode more quantum information compared to the qubit case, but it is a long-standing problem to entangle more than two such photons. In our experiment we use pulsed spontaneous parametric down-conversion to produce the photon quadruplets, which allows us to detect about one four-photon event per second. By means of quantum state reconstruction and a suitable witness operator we find that the photon quadruplets form a genuine multipartite entangled symmetric Dicke state. This opens a new tool for addressing foundational questions in quantum mechanics, and for exploration of novel high-dimensional multiparty quantum information applications such as secret sharing.
- Received 23 September 2015
DOI:https://doi.org/10.1103/PhysRevLett.116.073601
© 2016 American Physical Society
Physics Subject Headings (PhySH)
Synopsis
Entangled Quadruplet
Published 16 February 2016
Four photons are shown to be entangled through their orbital angular momentum.
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