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Spontaneous photon-pair generation from a dielectric nanoantenna

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The optical realization of a quantum computer, secure quantum communications and imaging requires fast and reliable generation of single photons and their quantum superpositions. Future quantum optical sources should be small as they will need to be integrated into future photonics devices so that they fit ‘on-chip’.

When an intense light impinges onto a nonlinear material, high energy photons can split into two. This interaction divides their energy, leaving a pair of lower energy photons which are entangled. The first demonstration of a nanoscale light source of entangled two-photon states was realized by a multinational team involving the DON group at laboratory MPQ.

These nanometric material structures are optical nanoantennas that strongly interact with light. Optical nano-antennas have already shown a great ability to manipulate photons efficiently, but their potential for production of multi-photon quantum states had remained unexplored.

In the framework of a multinational collaboration involving researchers in the UK, Australia, France, Italy and China, the group of Giuseppe Leo, with first author Giuseppe Marino, postdoctoral fellow in the DON team, has experimentally demonstrated the nanoscale generation of two-photon quantum states enhanced by the nanoscale semiconductor antenna. It is also easy to achieve the desired spectral response by changing the nano-antenna shape and geometry.

When excited by a laser, the nano-antenna generates pairs of photons at a much higher rate than usual methods. The research "Spontaneous photon-pair generation from a dielectric nanoantenna" is published in Optica.

These experiments pave the way to the development of nanoscale structures to generate multi-photon quantum states. Future applications include secure telecommunications and quantum imaging.

Giuseppe Leo (

Spontaneous photon-pair generation from a dielectric nanoantenna, G. Marino, A.S. Solntsev, L. Xu, V.F. Gili, L. Carletti, A.N. Poddubny, M. Rahmani, D.A. Smirnova, H.Chen, A. Lemaître, G. Zhang, A.V. Zayats, C. De Angelis, G. Leo, A.A. Sukhorukov, and D.N. Neshev, Optica 6, 1416 (2019)