{
  "abstract": "The Lorentz gas is a paradigmatic model in dynamical systems theory for understanding the origin of nonequilibrium transport in terms of microscopic deterministic chaos. In the periodic setting, a point particle scatters elastically off disks arranged on a two-dimensional lattice. Here we replace the disks by smooth potentials and the particle by the widely studied walking droplet, which propels itself on a vertically vibrating fluid. In the low-memory limit, this droplet reduces to a particle with nonlinear active friction. We call this system an active Lorentz gas. Using extensive numerical simulations, we analyze how dissipation generated by the active deterministic dynamics alters the phase-space structure of the corresponding conservative Lorentz gas. We find that islands of stability collapse into attracting and repelling sets. To characterize these structures, we introduce an energy-variance filtering method that distinguishes localized periodic, quasi-ballistic periodic, and chaotic trajectories, enabling the construction of bifurcation diagrams in a non-conservative setting. We identify parameter regimes exhibiting strong bifurcation cascades, anomalous diffusion, and significant phase-space contraction. Our results establish the active Lorentz gas as a rich framework for studying transport in dissipative dynamical systems and provide a bridge between active matter and classical models of chaotic transport, with potential implications for hydrodynamic quantum analogs in periodic media.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.02419",
  "author_total": 5,
  "authors": [
    {
      "name": "Aleksi Majaniemi"
    },
    {
      "name": "Esko Toivonen"
    },
    {
      "name": "Rahil N. Valani"
    },
    {
      "name": "Rainer Klages"
    },
    {
      "name": "Esa Räsänen"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/65dyq2d3v3eqg.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.02419",
  "fulltext_url": null,
  "id": "65dyq2d3v3eqg",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.02419",
  "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",
      "nlin.CD"
    ],
    [
      "openalex",
      "3109|Quantum chaos and dynamical systems"
    ]
  ],
  "openalex": "W7207589513",
  "pdf_url": "https://arxiv.org/pdf/2609.02419",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-19",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/65dyq2d3v3eqg.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:30:52Z",
      "native_id": "2609.02419",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.02419"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:nlin.CD",
      "subfield": "statistical-nonlinear"
    }
  ],
  "title": "An active Lorentz gas: walking droplets in periodic media",
  "title_text": "An active Lorentz gas: walking droplets in periodic media",
  "type": "preprint",
  "updated_at": "2026-10-30T12:33:41Z",
  "url": "https://research.draconitic.com/paper/65dyq2d3v3eqg",
  "venue": "arXiv",
  "versions": []
}