Photon Pairs from Resonant Metasurfaces

Abstract

All-dielectric optical metasurfaces are a workhorse in nano-optics, because of both their ability to manipulate light in different degrees of freedom and their excellent performance at light frequency conversion. Here, we demonstrate first-time generation of photon pairs via spontaneous parametric-down conversion in lithium niobate quantum optical metasurfaces with electric and magnetic Mie-like resonances at various wavelengths. By engineering the quantum optical metasurface, we tailor the photon-pair spectrum in a controlled way. Within a narrow bandwidth around the resonance, the rate of pair production is enhanced up to 2 orders of magnitude, compared to an unpatterned film of the same thickness and material. These results enable flat-optics sources of entangled photons—a new promising platform for quantum optics experiments.

Enhanced generation of nondegenerate photon pairs in nonlinear metasurfaces

“…Such predicted brightness enhancement is also much stronger than for MSs based on Mie-like resonances. 18…”

“…14 Traditionally, SPDC is performed in bulk nonlinear crystals with dimensions up to centimeters in length, while integrated waveguides have enabled a reduction of the footprint to millimeter 15 and down to 100 μm length scales. 16 At the subwavelength scale, generation of photon pairs was reported experimentally from a single AlGaAs nanoresonator 17 and lithium niobate MSs, 18 and studies were also conducted on monolayers of MoS 2 , 19 carbon nanotubes, 20 and directional emission from nanoresonators. 21 Importantly, SPDC in ultrathin nonlinear layers [22][23][24] can give rise to strong spatial correlations and allow quantum state engineering without the constraints of longitudinal phase matching.…”

Quantum Technologies for Engineering: the materials challenge

“…The photon pairs generated in lithium niobate and GaP nanofilms demonstrated a high coincidenceto-accidental ratio (∼700-1000) and an extremely broad spectrum (over 500 nm of bandwidth, spanning from 810 nm to 1350 nm), which was further enhanced by a Fabry-Perot effect in the film. This work laid the foundation for the future development of compact SPDC sources based on nonlinear metasurfaces, with the first demonstration published shortly after that work [87].…”

Two-Colour Spectrally Multimode Integrated SU(1,1) Interferometer

“…An excellent candidate for the source of squeezed and entangled photons in various linear and nonlinear interferometric schemes is the parametric down-conversion (PDC) process, which in the last few decades has been successfully realised in various nonlinear materials [15][16][17] and even recently in nanostructures [18,19]. Another fruitful nonlinear process is four-wave mixing (FWM), which can be implemented in waveguides, fibres [20], and even in atomic ensembles [21] to produce narrowband photon pairs with a long coherence time, which can be a great advantage in avoiding additional compensation techniques required for typical PDC-based photon sources.…”