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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2602.20012 |
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| _version_ | 1866915812356390912 |
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| author | Mcleod, Dylan Chiriano, Fabrizio Graffitti, Francesco Fedrizzi, Alessandro Gerardot, Brian D. Brotons-Gisbert, Mauro |
| author_facet | Mcleod, Dylan Chiriano, Fabrizio Graffitti, Francesco Fedrizzi, Alessandro Gerardot, Brian D. Brotons-Gisbert, Mauro |
| contents | Van der Waals (vdW) materials enable nonlinear-optical engineering with unprecedented resolution: their strong second-order susceptibilities ($χ^{(2)}$) and twist-tunable interlayer symmetry allow the effective nonlinearity to be shaped continuously, rather than through binary $\pmχ^{(2)}$ domain inversion as in bulk ferroelectrics. Here, we show that twist-angle domain engineering exploits this continuous degree of freedom to reconstruct target longitudinal nonlinearity profiles with high fidelity. Using spontaneous parametric down-conversion (SPDC) as a benchmark, we demonstrate that twist-engineered vdW crystals yield significantly improved approximations of target phase-matching functions and correspondingly higher single-photon purities, particularly in compact devices where fabrication constraints limit conventional approaches. We further show that this framework remains effective in experimentally relevant vdW materials and demanding non-degenerate wavelength regimes involving mid-infrared photons. More broadly, the ability to continuously and locally program $χ^{(2)}$ establishes a general framework for tailoring a wide range of SPDC properties, including absolute brightness, joint spectral amplitude structure, signal-idler frequency separation, and temporal wavepacket shape beyond what is accessible in conventional nonlinear crystals. These results position vdW heterostructures as a powerful platform for engineered quantum light sources and open new opportunities for nonlinear-optical devices shaped with monolayer thickness scale. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_20012 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Twist-Engineered Nonlinearity in Two-Dimensional Crystals for Tailored Quantum Light Mcleod, Dylan Chiriano, Fabrizio Graffitti, Francesco Fedrizzi, Alessandro Gerardot, Brian D. Brotons-Gisbert, Mauro Optics Van der Waals (vdW) materials enable nonlinear-optical engineering with unprecedented resolution: their strong second-order susceptibilities ($χ^{(2)}$) and twist-tunable interlayer symmetry allow the effective nonlinearity to be shaped continuously, rather than through binary $\pmχ^{(2)}$ domain inversion as in bulk ferroelectrics. Here, we show that twist-angle domain engineering exploits this continuous degree of freedom to reconstruct target longitudinal nonlinearity profiles with high fidelity. Using spontaneous parametric down-conversion (SPDC) as a benchmark, we demonstrate that twist-engineered vdW crystals yield significantly improved approximations of target phase-matching functions and correspondingly higher single-photon purities, particularly in compact devices where fabrication constraints limit conventional approaches. We further show that this framework remains effective in experimentally relevant vdW materials and demanding non-degenerate wavelength regimes involving mid-infrared photons. More broadly, the ability to continuously and locally program $χ^{(2)}$ establishes a general framework for tailoring a wide range of SPDC properties, including absolute brightness, joint spectral amplitude structure, signal-idler frequency separation, and temporal wavepacket shape beyond what is accessible in conventional nonlinear crystals. These results position vdW heterostructures as a powerful platform for engineered quantum light sources and open new opportunities for nonlinear-optical devices shaped with monolayer thickness scale. |
| title | Twist-Engineered Nonlinearity in Two-Dimensional Crystals for Tailored Quantum Light |
| topic | Optics |
| url | https://arxiv.org/abs/2602.20012 |