Metalens-array-based high-dimensional and multiphoton quantum source.

Li, Lin; Liu, Zexuan; Ren, Xifeng; Wang, Shuming; Su, Vin-Cent; Chen, Mu-Ku; Chu, Cheng Hung; Kuo, Hsin Yu et al. · Science · 2020

basic_science · Level V

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Abstract

The development of two-dimensional metasurfaces has shown great potential in quantum-optical technologies because of the excellent flexibility in light-field manipulation. By integrating a metalens array with a nonlinear crystal, we demonstrate a 100-path spontaneous parametric down-conversion photon-pair source in a 10 × 10 array, which shows promise for high-dimensional entanglement and multiphoton-state generation. We demonstrate two-, three- and four-dimensional two-photon path entanglement with different phases encoded by metalenses with fidelities of 98.4, 96.6, and 95.0%, respectively. Furthermore, four-photon and six-photon generation is observed with high indistinguishability of photons generated from different metalenses. Our metalens-array-based quantum photon source is compact, stable, and controllable, indicating a new platform for integrated quantum devices.