Publications

@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}

}

@article{Tan2026Direct,

title = {Direct Adaptive Certification of High-Dimensional Entanglement with Bell Tests},

author = {Xu Kang Tan and Jesvita Menezes and Sanjan D. Murthy and Adetunmise Charles Dada},

url = {https://arxiv.org/abs/2608.28235},

doi = {10.48550/arXiv.2608.28235},

year  = {2026},

date = {2026-08-28},

journal = {arXiv preprint arXiv:2608.28235},

abstract = {Entangled photons play a crucial role in quantum applications, and determining and characterising their entanglement is vital to using them effectively. High-dimensional entangled states offer richer possibilities, but their additional measurement degrees of freedom make them increasingly demanding to characterise. However, adaptive Bell-test methods based on complex simultaneous perturbation stochastic approximation (CSPSA) have so far focused mainly on qubits. Here we numerically investigate a Bell-inequality-violation-based method for detecting entanglement in unknown quantum states. We extend CSPSA to high-dimensional Bell testing by using the Collins-Gisin-Linden-Massar-Popescu (CGLMP) inequality for bipartite qudits. The resulting protocol can detect Bell-nonlocal correlations in unknown entangled states, whether pure or mixed, without first reconstructing their density matrix. Using 100 optimisation iterations in each of 100 independent finite-shot runs per number of dimensions d, we demonstrate certified CGLMP violations throughout d=2-8. For isotropic mixed states tested at a visibility of just 0.05 above the standard-Fourier violation threshold, we likewise observe confidence-certified CGLMP violations throughout the range of d studied. We compare this direct stochastic approach with quantum state tomography, the standard method for characterising an unknown state. In the matched benchmark, CSPSA uses fewer measurement configurations per attempt from d=6, whereas tomography requires fewer detected pairs per certified result through d=8. We also derive the phase dependence of the CGLMP parameter and clarify the features of its landscape that govern the adaptive search. Because the measurement-setting cost of each CSPSA iteration is independent of dimension, the method offers a particularly attractive route to the certification of high-dimensional entanglement.},

keywords = {High-dimensional entanglement, Quantum Entanglement, Quantum Measurements, Quantum optics},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevA.83.042339,

title = {Quantum measurements of atoms using cavity QED},

author = {Adetunmise Charles Dada and Erika Andersson and Martin L. Jones and Vivien M. Kendon and Mark S. Everitt},

url = {https://link.aps.org/doi/10.1103/PhysRevA.83.042339},

doi = {10.1103/PhysRevA.83.042339},

year  = {2011},

date = {2011-04-01},

journal = {Phys. Rev. A},

volume = {83},

issue = {4},

pages = {042339},

keywords = {Atoms, Cavity QED, Generalised measurements, POVMs, Quantum Measurements},

pubstate = {published},

tppubtype = {article}

}