2026
Secure Quantum Metasurfaces for Direct Quantum Key Distribution Measurements Journal Article
In: arXiv preprint arXiv:2609.22946, 2026.
@article{He2026Secure,
title = {Secure Quantum Metasurfaces for Direct Quantum Key Distribution Measurements},
author = {Yan He and Adetunmise Charles Dada},
url = {https://arxiv.org/abs/2609.22946},
doi = {10.48550/arXiv.2609.22946},
year = {2026},
date = {2026-09-19},
journal = {arXiv preprint arXiv:2609.22946},
abstract = {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.},
keywords = {Metasurface, POVMs, Quantum Measurements, Quantum optics},
pubstate = {published},
tppubtype = {article}
}
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.
Broadband Achromatic Metalens for the Short-Wave Infrared Journal Article
In: Scientific Reports, vol. 16, no. 1, pp. 22398, 2026.
@article{He2025,
title = {Broadband Achromatic Metalens for the Short-Wave Infrared},
author = {Yan He and Adetunmise Charles Dada},
url = {https://doi.org/10.1038/s41598-026-49825-0},
doi = {10.1038/s41598-026-49825-0},
year = {2026},
date = {2026-07-16},
urldate = {2025-01-01},
journal = {Scientific Reports},
volume = {16},
number = {1},
pages = {22398},
abstract = {The 1.8-2.3 mum band lies within the short-wavelength infrared (SWIR) region and serves as a key window for a wide range of applications, including quantum sensing, molecular spectroscopy, and free-space quantum and classical optical communication. Despite its significance, optical devices operating in this band still face two major challenges: chromatic aberration across the spectral range and difficulty of integration due to bulky optical elements. Metalenses are composed of subwavelength nanostructures that locally control the phase and group delay of light, enabling wavefront shaping and broadband dispersion compensation. These capabilities make them promising for infrared optical systems, particularly in focusing and imaging for compact devices. In this study, we propose a metalens design based on a CaF$_2$ substrate, where each nanocell consists of a silicon bar structure. These nanocells are periodically arranged with a 900~nm period, enabling control of dispersion and phase. By systematically finetuning the bar length and width, the design enables simultaneous dispersion compensation and phase modulation, achieving stable focusing performance over a broad spectral range. Finite-Difference Time-Domain (FDTD) simulations demonstrate effective suppression of chromatic aberration across 1800 - 2300 nm, with focal-length variation within 6% of the target value. We further analyze the polarization distribution across the focal spot and find a weak wavelength dependence of the degree of polarization (DoP), which we attribute to the spatially varying polarization state in the high-NA focal region together with the wavelength-dependent anisotropic response of the nanostructures. This design offers a compact, broadband, and high-performance approach for beam collimation and wavefront shaping in the SWIR band, showing promising potential for quantum communication and sensing systems.},
keywords = {achromatic metalens, chromatic aberration, Metasurface, optical communication, quantum sensing, short-wave infrared, SWIR},
pubstate = {published},
tppubtype = {article}
}
The 1.8-2.3 mum band lies within the short-wavelength infrared (SWIR) region and serves as a key window for a wide range of applications, including quantum sensing, molecular spectroscopy, and free-space quantum and classical optical communication. Despite its significance, optical devices operating in this band still face two major challenges: chromatic aberration across the spectral range and difficulty of integration due to bulky optical elements. Metalenses are composed of subwavelength nanostructures that locally control the phase and group delay of light, enabling wavefront shaping and broadband dispersion compensation. These capabilities make them promising for infrared optical systems, particularly in focusing and imaging for compact devices. In this study, we propose a metalens design based on a CaF$_2$ substrate, where each nanocell consists of a silicon bar structure. These nanocells are periodically arranged with a 900~nm period, enabling control of dispersion and phase. By systematically finetuning the bar length and width, the design enables simultaneous dispersion compensation and phase modulation, achieving stable focusing performance over a broad spectral range. Finite-Difference Time-Domain (FDTD) simulations demonstrate effective suppression of chromatic aberration across 1800 - 2300 nm, with focal-length variation within 6% of the target value. We further analyze the polarization distribution across the focal spot and find a weak wavelength dependence of the degree of polarization (DoP), which we attribute to the spatially varying polarization state in the high-NA focal region together with the wavelength-dependent anisotropic response of the nanostructures. This design offers a compact, broadband, and high-performance approach for beam collimation and wavefront shaping in the SWIR band, showing promising potential for quantum communication and sensing systems.
2022
An all-dielectric metasurface polarimeter Journal Article
In: ACS Photonics, vol. 9, no. 10, pp. 3245–3252, 2022.
@article{dada2022all,
title = {An all-dielectric metasurface polarimeter},
author = {Yash D Shah and Adetunmise Charles Dada and James P Grant and David RS Cumming and Charles Altuzarra and Thomas S Nowack and Ashley Lyons and Matteo Clerici and Daniele Faccio},
url = {https://doi.org/10.1021/acsphotonics.2c00395},
doi = {10.1021/acsphotonics.2c00395},
year = {2022},
date = {2022-09-15},
urldate = {2022-09-01},
journal = {ACS Photonics},
volume = {9},
number = {10},
pages = {3245--3252},
publisher = {American Chemical Society},
keywords = {all-dielectric materials, anapoles, Metasurface, metasurface-based polarimeters, Polarimetry, Stokes parameters},
pubstate = {published},
tppubtype = {article}
}