Advanced multi‐objective optimization of nonlinear metasurface unlocks quantum light generation

Kumela, Alemayehu Getahun and Lanteri, Stéphane and Papoff, Francesco and Jeffers, John and Leo, Giuseppe and Lecasble, Célestin and Gérard, Jean‐Michel and Elsawy, Mahmoud (2026) Advanced multi‐objective optimization of nonlinear metasurface unlocks quantum light generation. Advanced Optical Materials, 14 (12). e03793. ISSN 2195-1071 (https://doi.org/10.1002/adom.202503793)

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Abstract

The design of nonlinear metasurfaces for quantum applications has traditionally focused on classical figures of merit such as tuning resonances at the pump and target frequencies. While these approaches can enhance nonlinear efficiency, they do not guarantee the precise phase control needed for generating pure quantum state. In this work, we present a hybrid quantum‐classical inverse design framework that directly incorporates quantum metrics into the optimization process. By leveraging an advanced multiobjective optimization, we optimized both entanglement fidelity and the spontaneous parametric down conversion (SPDC) rate, ensuring that high brightness and quantum purity are achieved simultaneously. In general, classical methods that rely on bound states in the continuum (BIC) modes or sharp resonances, can improve the SPDC rate but are often sensitive and difficult to control across the polarization channels leading to low quantum purity, uncontrolled correlations, and reduced entanglement fidelity. In contrast, our approach demonstrates that reliable, easy‐to‐fabricate metasurfaces can achieve superior quantum performance without these constraints. When applied to a [100] AlGaAs nanohole metasurface, our numerical simulations predict a Bell‐state fidelity of 0.989 combined with a collected SPDC rate of 55 Hz/mW, integrated over a wide angular emission range. Our optimized design represents a robust architecture for compact, high‐purity sources of entangled photon pairs.

ORCID iDs

Papoff, Francesco ORCID: https://orcid.org/0000-0002-3456-343X

Jeffers, John ORCID: https://orcid.org/0000-0002-8573-1675

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• Item metadata

  Item type:	Article
  ID code:	96170
  Dates:	Date Event 25 March 2026 Published 9 March 2026 Published Online 26 February 2026 Accepted 24 November 2025 Submitted
  Subjects:	Science > Physics > Optics. Light
  Department:	Faculty of Science > Physics
  Depositing user:	Pure Administrator
  Date deposited:	05 May 2026 09:07
  Last modified:	05 Jun 2026 18:50
  URI:	https://strathprints.strath.ac.uk/id/eprint/96170