{
  "abstract": "High-harmonic generation (HHG) is conventionally understood to produce attosecond pulse trains only when the emitted harmonics are mutually phase-locked, in accordance with the classical theory of mode-locking. Such locking is necessary for pulse synthesis when the harmonic field is in a separable multimode quantum state. This requirement, however, can be circumvented entirely for harmonic combs exhibiting intermodal entanglement. We introduce a novel family of multimode quantum states, termed attoquants: states associated with highly structured pulse trains that are inherently insensitive to relative phases. As a concrete example, we analyse the coherent permanent state, constructed as a completely symmetric superposition of products of coherent states over all permutations of a fixed parameter set. It is shown analytically that its electric-field expectation value is a locked Fourier superposition of the driving-field harmonics, yielding an attosecond pulse train without requiring mode-locking. We further calculate the photon statistics, the Wigner function, and the logarithmic negativity of this state, confirming it to be genuinely nonclassical and entangled. Finally, we offer a phenomenological interpretation for the generation of such entangled states during HHG, as a consequence of multi-atom effects. Since the coherence volume of the driving field greatly exceeds that of its harmonics, a collectively-driven cluster of atoms can radiate the individual harmonics as spatially resolved, but fundamentally indistinguishable sources. This can generate the permutation-symmetric entanglement structure of an attoquant.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.17854",
  "author_total": 2,
  "authors": [
    {
      "name": "Sándor Varró"
    },
    {
      "name": "Ákos Gombkötő"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/38crvjfe4yv61.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.17854",
  "fulltext_url": null,
  "id": "38crvjfe4yv61",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.17854",
  "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",
      "quant-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2608.17854",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-06",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/38crvjfe4yv61.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:22Z",
      "native_id": "2608.17854",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.17854"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "A quantum optical concept of attosecond pulses: the attoquants",
  "title_text": "A quantum optical concept of attosecond pulses: the attoquants",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:22Z",
  "url": "https://research.draconitic.com/paper/38crvjfe4yv61",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1088/1367-2630/aeb044",
      "pid": "61zxgwznteezy",
      "relation": "published-as",
      "title": "A quantum optical concept of attosecond pulses: the attoquants",
      "venue": "New Journal of Physics"
    }
  ]
}