Exciton-Enhanced Spontaneous Parametric Down-Conversion in Two-Dimensional Crystals
Fengyuan Xuan, M.O. Lai, Yaze Wu, Su Ying Quek
Abstract
We show that excitonic resonances and interexciton transitions can enhance the probability of spontaneous parametric down-conversion, a second-order optical response that generates entangled photon pairs. We benchmark our ab initio many-body calculations using experimental polar plots of second harmonic generation in NbOI_{2}, clearly demonstrating the relevance of excitons in the nonlinear response. A strong double-exciton resonance in 2D NbOCl_{2} leads to giant enhancement in the second order susceptibility. Our work paves the way for the realization of efficient ultrathin quantum light sources.
Topics & Concepts
ExcitonMaterials scienceParametric statisticsSpontaneous parametric down-conversionAtomic physicsOptoelectronicsOpticsPhysicsCondensed matter physicsQuantum mechanicsQuantumMathematicsStatisticsQuantum entanglementSpectroscopy and Quantum Chemical StudiesQuantum optics and atomic interactionsRandom lasers and scattering media