{
  "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": [
    "Tampere University Faculty of Engineering and Natural Sciences",
    "University of Oxford",
    "Queen Mary University of London"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Aleksi Majaniemi",
      "orcid": "0009-0004-0055-3243"
    },
    {
      "affs": [
        0
      ],
      "name": "Esko Toivonen",
      "orcid": "0000-0002-3151-2805"
    },
    {
      "affs": [
        1
      ],
      "name": "Rahil Valani",
      "orcid": "0000-0001-8346-0739"
    },
    {
      "affs": [
        2
      ],
      "name": "Rainer Klages",
      "orcid": "0000-0003-3811-3070"
    },
    {
      "affs": [
        0
      ],
      "name": "Esa Räsänen",
      "orcid": "0000-0001-8736-4496"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ajjh2wggeqe43.bib",
  "cited_by": 0,
  "doi": "10.1088/1367-2630/aebdbe",
  "fulltext_url": null,
  "id": "ajjh2wggeqe43",
  "issns": [
    "1367-2630"
  ],
  "landing_url": "https://iopscience.iop.org/article/10.1088/1367-2630/aebdbe",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [],
  "openalex": null,
  "pdf_url": "https://iopscience.iop.org/article/10.1088/1367-2630/aebdbe/pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-04",
  "publisher": "IOP Publishing",
  "ris": "https://research.draconitic.com/paper/ajjh2wggeqe43.ris",
  "sources": [
    {
      "first_seen": "2026-11-05T00:20:40Z",
      "native_id": "10.1088/1367-2630/aebdbe",
      "source": "crossref",
      "url": "https://iopscience.iop.org/article/10.1088/1367-2630/aebdbe"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "journal-openalex:3107|Quantum Mechanics and Applications",
      "subfield": "amo"
    }
  ],
  "title": "An active Lorentz gas: walking droplets in periodic media",
  "title_text": "An active Lorentz gas: walking droplets in periodic media",
  "type": "peer-reviewed",
  "updated_at": "2026-11-06T00:20:56Z",
  "url": "https://research.draconitic.com/paper/ajjh2wggeqe43",
  "venue": "New Journal of Physics",
  "versions": []
}