Quantum Pair Generation in Nonlinear Metasurfaces with Mixed and Pure Photon Polarizations

• Published in: Nano letters 2024-12, Vol.24 (48), p.15356-15362
• Main Authors: Noh, Jiho, Santiago-Cruz, Tomás, Sultanov, Vitaliy, Doiron, Chloe F., Gennaro, Sylvain D., Chekhova, Maria V., Brener, Igal
• Format: Article
• Language: English
• Subjects: Bound States in the Continuum; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Nonlinear Metasurfaces; Photon-Pair Generation; Polarization Engineering; Quantum optics; Spontaneous Parametric Down-Conversion
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/acs.nanolett.4c04398

Metasurfaces are highly effective at manipulating classical light in the linear regime; however, effectively controlling the polarization of nonclassical light generated from nonlinear resonant metasurfaces remains a challenge. Here, we present a solution by achieving polarization engineering of frequency-nondegenerate biphotons emitted via spontaneous parametric down-conversion in GaAs metasurfaces, utilizing quasi-bound states in the continuum (qBIC) resonances to enhance biphoton generation. Through comprehensive polarization tomography, we demonstrate that the emitted photons’ polarization directly reflects the qBIC mode’s far-field properties. Furthermore, we show that both the type of qBIC mode and the symmetry of the meta-atoms can be tailored to control each single-photon polarization state, and that the subsequent two-photon polarization states are nearly separable, offering potential applications in the heralded generation of single photons with adjustable polarization. This work provides a significant step toward utilizing metasurfaces to generate quantum light and engineer their polarization, a critical aspect for future quantum technologies.