{
  "abstract": "In this paper, we study the effect of a which-path memory ancilla on the three-slit interference pattern within the framework of the bright--dark state description [Phys. Rev. Lett. 134, 133603 (2025)]. Whereas two slits give one bright mode, a photonic mode that couples to the detector atoms, and one dark mode, which does not couple to the detector atoms, three slits lead to one detector-coupled bright mode and a two-dimensional dark-mode subspace in the three-dimensional path space. We first discuss the classical three-slit interference pattern in terms of probability leakage into the dark subspace. We then study the von Neumann entropy $S_D$ of the dark subspace and the coherence measures of the reduced photonic state obtained by tracing out the memory: dark-sector coherence $C_D$ and bright--dark coherence $C_{BD}$. These quantities bring out the internal quantum structure of the two-dimensional dark subspace. We show that, whereas $C_D$ is not by itself a basis-independent physical observable, $C_{BD}$ is basis-invariant. We establish that, for two paths, $C_{BD}$ is fixed entirely by the populations and the single pairwise coherence, whereas for multiple paths, $M\\geq 3$, it acquires a genuinely multipath contribution generated by asymmetry among the pairwise which-path overlaps. Finally, we distinguish the part of the path-coherence loss that is recoverable through a suitable measurement of the memory from the irreducible coherence deficit imposed by an uncontrolled environment.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.24243",
  "author_total": 3,
  "authors": [
    {
      "name": "Ajay Kumar"
    },
    {
      "name": "Guruprasad Kadam"
    },
    {
      "name": "Anirban Pathak"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/e8tqt99mev6y8.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.24243",
  "fulltext_url": null,
  "id": "e8tqt99mev6y8",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.24243",
  "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",
      "3107|Quantum Mechanics and Applications"
    ]
  ],
  "openalex": "W7204228419",
  "pdf_url": "https://arxiv.org/pdf/2608.24243",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/e8tqt99mev6y8.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:00Z",
      "native_id": "2608.24243",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.24243"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Three-slit interference with a which-path memory ancilla: A bright-dark state formulation",
  "title_text": "Three-slit interference with a which-path memory ancilla: A bright-dark state formulation",
  "type": "preprint",
  "updated_at": "2026-10-30T12:18:00Z",
  "url": "https://research.draconitic.com/paper/e8tqt99mev6y8",
  "venue": "arXiv",
  "versions": []
}