{
  "abstract": "We study thermalisation and the possible occurrence of the Mpemba effect in a closed quantum setting that mimics the interaction of a system with thermal reservoirs coupled only at its boundaries. Specifically, we consider a tripartite geometry in which a finite chain, initially prepared at a finite temperature, is suddenly connected on both sides to two semi-infinite chains of the same nature held at a different temperature. These outer chains act as thermal baths, while the full system evolves unitarily under a homogeneous Hamiltonian. This setup provides a simple quantum realisation of a temperature quench and closely resembles the original scenario in which the classical Mpemba effect was first observed. We focus on two paradigmatic free-fermion models, the XX chain and the transverse-field Ising chain, which respectively preserve and break the global $U(1)$ particle-number symmetry. As a probe of relaxation, we consider the Frobenius distance between the time-evolved reduced density matrix of the central subsystem and its stationary state, which is the thermal state at the bath temperature. Exploiting the free-fermionic structure of both models, the dynamics remains Gaussian and the Frobenius distance can be expressed exactly in terms of two-point correlation functions. Combining this representation with generalised hydrodynamics, we derive analytical predictions for the Frobenius distance in the hydrodynamic limit, providing a complete characterisation of the thermalisation process. Using these results, we investigate the possible occurrence of the Mpemba effect. We find that, despite the genuine non-equilibrium dynamics displayed by the system, no Mpemba effect arises in this setting. Our analysis identifies a broad class of boundary-driven thermalisation protocols in which relaxation is fully characterised analytically and exhibits no anomalous acceleration of equilibration.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: J. Stat. Mech. (2026) 103104",
  "arxiv": "2606.06362",
  "author_total": 3,
  "authors": [
    {
      "name": "Purvaash Panduranghan-Udhayashankar"
    },
    {
      "name": "Filiberto Ares"
    },
    {
      "name": "Pasquale Calabrese"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ehwb9xr28bd78.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2606.06362",
  "fulltext_url": null,
  "id": "ehwb9xr28bd78",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2606.06362",
  "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",
      "cond-mat.stat-mech"
    ],
    [
      "arxiv",
      "quant-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2606.06362",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-15",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ehwb9xr28bd78.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:50Z",
      "native_id": "2606.06362",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2606.06362"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.stat-mech",
      "subfield": "statistical-nonlinear"
    }
  ],
  "title": "A closed system setting for quantum thermalisation in free fermions",
  "title_text": "A closed system setting for quantum thermalisation in free fermions",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:50Z",
  "url": "https://research.draconitic.com/paper/ehwb9xr28bd78",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1088/1742-5468/aea559",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}