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WAVE-Particle Duality Entanglement Observed


Amongst the properties of matter described by quantum physics, there is the dual nature of each particle that acts simultaneously as a wave and as matter, as well as a deep correlation - even over large distances - between microscopic particle systems, such as photons. Although these two phenomena commonly referred to as "wave-particle duality" and "entanglement" (which Einstein referred to as "spooky action at a distance") have been separately verified various times, they have never been analysed in terms of their mutual relationship.

A new study published on Nature Communications, which was coordinated at the experimental level in the Sapienza Department of Physics Quantum Information Laboratory by Fabio Sciarrino and at the theoretical level by Rosario Franco from the Department of Energy, Information Engineering and Mathematical Models at the University of Palermo, together with researchers from other universities in China and Vietnam, has demonstrated that these two fundamental aspects of quantum mechanics can coexist.

The international group of physicists achieved this result through the experimental implementation of a theoretical scheme employing polarized photons: light particles with a specific oscillating direction.

The first step in the project was to prove that a single photon could manifest itself simultaneously as a wave and as a particle in thes quantum overlapping of these two behaviours. Subsequently, the physicists created and observed two photons whose wave- or particle-like behaviour was determined by the dual behaviour of the other, regardless of the distance between the two photons.

“We have shown that a two-photon entanglement in their dual-wave particle nature is possible,” explains Professor Lo Franco. “This phenomenon, in analogy with Einstein's picturesque expression, can thus be referred to as distance-wave duality action and it can be extended to multiple photons thanks to the simplicity of our theoretical scheme and the effectiveness of our experimental apparatus."

The Sapienza team produced a highly stable, modular device that can be replicated for a growing number of particles and completely automatized. "We are now working,” Professor Sciarrino points out, “in two new directions. From a conceptual point of view, our aim is to develop the quantifiers ("witnesses") of quantum resources, both theoretically and experimentally; while, from a technological point of view, we are developing an integrated optical-based platform so that we can increase the complexity of the generated states for applications in the fields of cryptography and quantum communications."


Adil S. Rab, Emanuele Polino, Zhong-Xiao Man, Nguyen Ba An, Yun-Jie Xia, Nicolò Spagnolo, Rosario Franco & Fabio Sciarrino -  Entanglement of Photons in their Dual Wave-Particle Nature, Nature Communications 8, Article Number: 915 (2017), DOI: 10.1038/ s41467-017-01058-6.