One Aperture, Two Colors: Depth-Allocated Bilayer Silicon Nitride Gratings for Trapped-Ion Addressing
Abstract
Scaling multicolor quantum control on chip presents a geometric conflict: each added wavelength traditionally requires another routing corridor, emitter, and electrode opening, consuming trap-surface area and exposing charge-susceptible dielectric near the quantum target. This work introduces an all-planar, vertically stacked silicon-nitride architecture that co-registers independently fed optical transitions within one 24 x 24 μm footprint. For 40Ca+, the device focuses the 729.4 nm qubit and 854.2 nm repump wavelengths onto a shared site 70 μm above the upper film. A hierarchical design combines a differentiable cell search for a three-level scatterer, analytic confocal phase synthesis, and deterministic depth allocation across two etches per layer, preserving an explicit 125 nm propagation-axis line-and-space floor without grayscale patterning. Retargeting the upper-layer phase co-registers the focal maxima to within 0.1 μm in mesh-converged Tidy3D and independently constructed Lumerical FDTD models, retaining >99.9% of each color's peak intensity at the common coordinate with focusing efficiencies of 0.410 and 0.168. At 5 μm ion spacing, the qubit channel reaches -24.8 dB point crosstalk, remains below -18.0 dB across a 0.5 μm-radius positioning disk, and yields -23.0 dB symmetric-traceless field-gradient suppression. In the analytic House conductor geometry, the shared footprint provides 15.3 μm clearance to the nearest radio-frequency rail with zero RF-null displacement. By uniting separate optical inputs and transition-specific wavefronts within one ion-facing aperture, this hierarchy establishes a transferable template for addressing other atomic wavelength pairs and dense multicolor quantum interfaces.
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BibTeX
@misc{yadav2026aperture,
title = {{One Aperture, Two Colors: Depth-Allocated Bilayer Silicon Nitride Gratings for Trapped-Ion Addressing}},
author = {Gyanendra Yadav},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.23529},
eprint = {2607.23529},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.23529},
}
RIS
TY - UNPB
TI - One Aperture, Two Colors: Depth-Allocated Bilayer Silicon Nitride Gratings for Trapped-Ion Addressing
AU - Gyanendra Yadav
PY - 2026
DA - 2026/09/20
PB - arXiv
DO - 10.48550/arxiv.2607.23529
UR - https://arxiv.org/abs/2607.23529
AB - Scaling multicolor quantum control on chip presents a geometric conflict: each added wavelength traditionally requires another routing corridor, emitter, and electrode opening, consuming trap-surface area and exposing charge-susceptible dielectric near the quantum target. This work introduces an all-planar, vertically stacked silicon-nitride architecture that co-registers independently fed optical transitions within one 24 x 24 μm footprint. For ^40Ca^+, the device focuses the 729.4 nm qubit and 854.2 nm repump wavelengths onto a shared site 70 μm above the upper film. A hierarchical design combines a differentiable cell search for a three-level scatterer, analytic confocal phase synthesis, and deterministic depth allocation across two etches per layer, preserving an explicit 125 nm propagation-axis line-and-space floor without grayscale patterning. Retargeting the upper-layer phase co-registers the focal maxima to within 0.1 μm in mesh-converged Tidy3D and independently constructed Lumerical FDTD models, retaining >99.9% of each color's peak intensity at the common coordinate with focusing efficiencies of 0.410 and 0.168. At 5 μm ion spacing, the qubit channel reaches -24.8 dB point crosstalk, remains below -18.0 dB across a 0.5 μm-radius positioning disk, and yields -23.0 dB symmetric-traceless field-gradient suppression. In the analytic House conductor geometry, the shared footprint provides 15.3 μm clearance to the nearest radio-frequency rail with zero RF-null displacement. By uniting separate optical inputs and transition-specific wavefronts within one ion-facing aperture, this hierarchy establishes a transferable template for addressing other atomic wavelength pairs and dense multicolor quantum interfaces.
ER -