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arXiv · 2003.09961

Bell inequality violation by entangled single photon states generated from a laser, a LED or a Halogen lamp

M. Pasini·N. Leone·S. Mazzucchi·V. Moretti·D. Pastorello·L. Pavesi
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Abstract

In single-particle or intraparticle entanglement, two degrees of freedom of a single particle, e.g., momentum and polarization of a single photon, are entangled. Single-particle entanglement (SPE) provides a source of non classical correlations which can be exploited both in quantum communication protocols and in experimental tests of noncontextuality based on the Kochen-Specker theorem. Furthermore, SPE is robust under decoherence phenomena. Here, we show that single-particle entangled states of single photons can be produced from attenuated sources of light, even classical ones. To experimentally certify the entanglement, we perform a Bell test, observing a violation of the Clauser, Horne, Shimony and Holt (CHSH) inequality. On the one hand, we show that this entanglement can be achieved even in a classical light beam, provided that first-order coherence is maintained between the degrees of freedom involved in the entanglement. On the other hand, we prove that filtered and attenuated light sources provide a flux of independent SPE photons that, from a statistical point of view, are indistinguishable from those generated by a single photon source. This has important consequences, since it demonstrates that cheap, compact, and low power entangled photon sources can be used for a range of quantum technology applications.

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M. Pasini, N. Leone, S. Mazzucchi, V. Moretti, D. Pastorello, L. Pavesi. 2020-03-22. Bell inequality violation by entangled single photon states generated from a laser, a LED or a Halogen lamp. https://doi.org/10.1103/physreva.102.063708

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