{
  "abstract": "Mechanically compliant mirrors are key components in cavity optomechanics. However, the requirements to achieve the best optical and mechanical performance are usually in direct competition. A high reflectivity for tightly focused beams entails thick reflectors, whereas ultracoherent flexural nanomechanics necessitates thin membranes. We eliminate this trade-off by introducing high-refractive-index nanopillar metasurfaces on top of a thin membrane. We pattern a 50 micrometer-diameter array of nanopillars to form a photonic crystal. The flat band behavior of guided resonances in the photonic crystal enables a reflectivity of 99.82(1)% for a tightly focused beam of 7 micrometer waist. The combination of two guided resonances creates a 100 nanometer-wide high-reflectivity band around 1550 nanometer. Simultaneously, the nanopillar patterning realizes a density-modulated phononic crystal that isolates an ultracoherent localized mechanical mode with a $Q\\cdot f$-product of $2\\cdot 10^{14}$Hz. The demonstrated nanopillar metasurfaces enable lightweight mirrors for room-temperature quantum optomechanics and for use as levitated mirrors or lightsails.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.31452",
  "author_total": 9,
  "authors": [
    {
      "name": "Alexander Jung"
    },
    {
      "name": "Anastasiia Ciers"
    },
    {
      "name": "Hannes Pfeifer"
    },
    {
      "name": "Albert Hansson"
    },
    {
      "name": "Johanna Örgård"
    },
    {
      "name": "Daniel Stachanow"
    },
    {
      "name": "Viktor A. Lilja"
    },
    {
      "name": "Philippe Tassin"
    },
    {
      "name": "Witlef Wieczorek"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bqy9m3yt1fzvb.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.31452",
  "fulltext_url": null,
  "id": "bqy9m3yt1fzvb",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.31452",
  "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.app-ph"
    ],
    [
      "arxiv",
      "physics.optics"
    ],
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "3107|Mechanical and Optical Resonators"
    ]
  ],
  "openalex": "W7223374052",
  "pdf_url": "https://arxiv.org/pdf/2610.31452",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bqy9m3yt1fzvb.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:34Z",
      "native_id": "2610.31452",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.31452"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.app-ph",
      "subfield": "applied-instrumentation"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.optics",
      "subfield": "optics-photonics"
    },
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Nanopillar metasurfaces uniting high optical reflectivity with ultracoherent nanomechanics",
  "title_text": "Nanopillar metasurfaces uniting high optical reflectivity with ultracoherent nanomechanics",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:34Z",
  "url": "https://research.draconitic.com/paper/bqy9m3yt1fzvb",
  "venue": "arXiv",
  "versions": []
}