{
  "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 $μ$m footprint. For $^{40}\\text{Ca}^+$, the device focuses the 729.4 nm qubit and 854.2 nm repump wavelengths onto a shared site 70 $μ$m 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 $μ$m 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 $μ$m ion spacing, the qubit channel reaches -24.8 dB point crosstalk, remains below -18.0 dB across a 0.5 $μ$m-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 $μ$m 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.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2607.23529",
  "author_total": 1,
  "authors": [
    {
      "name": "Gyanendra Yadav"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bcqszkcfsjcpj.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2607.23529",
  "fulltext_url": null,
  "id": "bcqszkcfsjcpj",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2607.23529",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.optics"
    ],
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "2208|Photonic and Optical Devices"
    ]
  ],
  "openalex": "W7171548983",
  "pdf_url": "https://arxiv.org/pdf/2607.23529",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bcqszkcfsjcpj.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:19Z",
      "native_id": "2607.23529",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2607.23529"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.optics",
      "subfield": "optics-photonics"
    },
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "One Aperture, Two Colors: Depth-Allocated Bilayer Silicon Nitride Gratings for Trapped-Ion Addressing",
  "title_text": "One Aperture, Two Colors: Depth-Allocated Bilayer Silicon Nitride Gratings for Trapped-Ion Addressing",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:19Z",
  "url": "https://research.draconitic.com/paper/bcqszkcfsjcpj",
  "venue": "arXiv",
  "versions": []
}