{
  "abstract": "Low-resolution digital-to-analog conversion can simplify continuous-variable quantum key distribution (CVQKD) transmitters, but coarse quantization increases excess noise and can generate data-correlated spectral replicas. We demonstrate digital delta--sigma modulation (DSM) for low-resolution waveform generation in Gaussian-modulated CVQKD. In a 500-MBaud CVQKD system over 20~km of fiber, 3-bit second-order DSM achieves an estimated asymptotic secret key rate of 46.38~Mbps at an oversampling ratio of 12, whereas uniform quantization yields no positive rate. With 4-bit second-order DSM, the rate reaches 50.11~Mbps, approximately 97\\% of the 12-bit reference. A noise model combining the DSM noise-transfer function with matched filtering guides the sampling-rate and signal-band design for effective noise suppression. We also identify a phase-conjugate spectral replica arising from third-order intermodulation between the pilot tone and quantum signal, and evaluate its key-rate penalty using a linear-replica security model. At 3-bit resolution and an oversampling ratio of 24, first-order DSM reduces the experimentally estimated leakage-mode strength by approximately four orders of magnitude. Together, our findings establish the security boundaries and operating conditions of DSM, providing design guidance for low-resolution CVQKD transmitters.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.23654",
  "author_total": 3,
  "authors": [
    {
      "name": "Wenjun Fan"
    },
    {
      "name": "Zhenlin Zhao"
    },
    {
      "name": "Dawei Wang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5vhzvex2mkpfh.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.23654",
  "fulltext_url": null,
  "id": "5vhzvex2mkpfh",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.23654",
  "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",
      "1702|Quantum Information and Cryptography"
    ]
  ],
  "openalex": "W7222963046",
  "pdf_url": "https://arxiv.org/pdf/2610.23654",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/5vhzvex2mkpfh.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:30:32Z",
      "native_id": "2610.23654",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.23654"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Delta-sigma noise shaping for low-resolution quantization in Gaussian-modulated continuous-variable quantum key distribution",
  "title_text": "Delta-sigma noise shaping for low-resolution quantization in Gaussian-modulated continuous-variable quantum key distribution",
  "type": "preprint",
  "updated_at": "2026-10-30T12:33:28Z",
  "url": "https://research.draconitic.com/paper/5vhzvex2mkpfh",
  "venue": "arXiv",
  "versions": []
}