用于直接量子密钥分发测量的安全量子超表面
Secure Quantum Metasurfaces for Direct Quantum Key Distribution Measurements
- University of Glasgow（格拉斯哥大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出用超表面直接实现QKD测量，设计亚波长多波长孔径映射BB84协议，实现高保真、低误码的紧凑被动接收器，为小型化QKD设备开辟新路径。
AI中文摘要：
量子密钥分发（QKD）能够提供信息论安全性，但其接收器通常仍由级联的体光学元件组装而成。超表面为大幅降低这种复杂性提供了可能。在此，我们让超表面本身充当QKD测量装置。我们设计了波长特定的介质孔径，工作波长分别为780、1550、2000和10600纳米，这些孔径以0.44至0.49λ的单元间距（即低于工作波长的一半）交织了线偏振H/V和圆偏振R/L相位库，并将完整的被动BB84测量直接映射到四个探测器通道上。这种亚波长基矢共置设计防止了普通传播波孔径掩模在不衰减或扰动另一基矢的情况下隔离单一基矢。模拟的全波焦平面强度通过拟合的、校准固定的探测器区域直接转换为条件Born概率。所选设计实现了97.96%至99.08%的概率保真度，四端口收集效率为17.43%至40.94%，平均固有量子比特错误率为1.42%至3.96%。在1550纳米波长下，所选设计在理想单光子模型下给出了每入射光子0.151个安全比特的渐近器件级产率。六态探测器层析成像为所有六个重建的接收器模型（包括其偏振相关损耗、基矢不平衡和串扰）提供了正的双基矢安全界限。这些结果确立了协议匹配的元光学作为紧凑、被动QKD接收器的途径。
英文摘要：
Quantum key distribution (QKD) can deliver information-theoretic security, but its receivers are still typically assembled from cascaded bulk optics. Metasurfaces offer a radical reduction in this complexity. Here, we make the metasurface function as the QKD measurement device itself. We design wavelength-specific dielectric apertures at 780, 1550, 2000, and 10 600 nm that interweave the linear H/V and circular R/L phase libraries at a 0.44--0.49λ cell pitch, i.e., below half the operating wavelength, and map the complete passive-BB84 measurement directly onto four detector channels. This subwavelength basis co-location prevents an ordinary propagating-wave aperture mask from isolating one basis without simultaneously attenuating or perturbing the other. Simulated full-wave focal-plane intensities are converted directly into conditional Born probabilities using fitted, calibration-fixed detector regions. The selected designs achieve probability fidelities of 97.96--99.08%, four-port collected efficiencies of 17.43--40.94%, and mean intrinsic quantum bit error rates of 1.42--3.96%. At 1550 nm, the selected design gives an asymptotic device-level yield of 0.151 secret bits per incident photon under an ideal single-photon model. Six-state detector tomography gives positive both-basis security bounds for all six reconstructed receiver models, including their polarization-dependent loss, basis imbalance and crosstalk. These results establish protocol-matched meta-optics as a route to compact, passive QKD receivers.
