{
  "abstract": "Telecom-band silicon spin-photon qubits offer a promising platform for scalable quantum networks and distributed information processing, but their fixed emission wavelengths require compact, low-loss beam splitters with precise splitting and fabrication robustness. Conventional designs can face trade-offs between footprint, optical performance, and wavelength-specific operation. Here, we employ adjoint-based inverse design to optimize photonic geometries beyond conventional layouts, developing 1*2 Y-splitters and 2*2 directional couplers for the silicon T (1326 nm) and Al1 (1482.44 nm) spin-photon qubits. The devices achieve footprints of 2.9 and 26 um^2, respectively, with excess losses of 0.14-0.44 dB and back-reflection below 5*10^-4. We assess fabrication tolerance using 100-realization Monte Carlo simulations incorporating etch bias, line-edge roughness, thickness, and refractive-index variations. Mirror symmetry reduces the splitting-ratio spread of the Y-splitter by a factor of seven to nine relative to the directional coupler. We translate these variations into dual-rail fidelity, ideal splitting-ratio-limited Hong-Ou-Mandel visibility, and random-number min-entropy. All realizations satisfy a protocol-performance threshold of 0.95. At 0.99, the tolerated splitting-ratio deviation shrinks from 0.035 for visibility to 0.0035 for min-entropy, and the simulated yields are 68% (T) and 91% (Al1) for coupler visibility and 90% (T) and 66% (Al1) for Y-splitter min-entropy. The tolerance of the target protocol, rather than the device alone, therefore sets the fabrication requirement for silicon spin-photon beam splitters.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2611.02209",
  "author_total": 3,
  "authors": [
    {
      "name": "Nail Letty"
    },
    {
      "name": "Tahmeed Ul Islam"
    },
    {
      "name": "Wayesh Qarony"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1azgq44h7p17p.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2611.02209",
  "fulltext_url": null,
  "id": "1azgq44h7p17p",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2611.02209",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "quant-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2611.02209",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1azgq44h7p17p.ris",
  "sources": [
    {
      "first_seen": "2026-11-03T12:20:59Z",
      "native_id": "2611.02209",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2611.02209"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "From Fabrication Disorder to Quantum-Protocol Yield in Inverse-Designed Silicon Photonic Beam Splitters",
  "title_text": "From Fabrication Disorder to Quantum-Protocol Yield in Inverse-Designed Silicon Photonic Beam Splitters",
  "type": "preprint",
  "updated_at": "2026-11-05T15:20:18Z",
  "url": "https://research.draconitic.com/paper/1azgq44h7p17p",
  "venue": "arXiv",
  "versions": []
}