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arXiv:2603.17078 · Physical review. E

Quantifying entanglement in quantum thermodynamics via separability constraints

Joan Alba, Laura Ares, Jan Sperling, Julien Pinske

quant-phSubmitted Mar 17, 2026• Announced Mar 19, 2026• 0 citations• Revised Mar 20, 2026 (v2)
v1 · Mar 17, 2026v2 · Mar 20, 2026v3 · Oct 26, 2026
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Abstract

The role of quantum entanglement in thermodynamical systems remains elusive. Does entanglement result in thermodynamic advantages or does it impose fundamental limitations? Here, we unambiguously quantify the amount of heat and work in a quantum system that is due to the presence of entanglement. This is achieved by constraining the system's non-equilibrium dynamics to separable states, thereby isolating the impact entanglement has on thermodynamic effects. Unlike thermodynamic entanglement measures, which signify a loose connection between entanglement and thermodynamic properties, imposing a constraint constitutes an active intervention into a system -- answering how much of a system's thermodynamics is caused by (not correlated with) its quantumness. We benchmark our theory by applying the constrained dynamics to several multipartite systems, including quantum batteries and quantum refrigerators.

Journal reference
Phys. Rev. E 114, 024157 (2026)
DOI
10.1103/sjqy-gnvp
Comments
14 pages, 6 figures

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The role of quantum entanglement in thermodynamical systems remains elusive. Does entanglement result in thermodynamic advantages or does it impose fundamental limitations? Here, we unambiguously quantify the amount of heat and work in a quantum system that is due to the presence of entanglement. This is achieved by constraining the system's non-equilibrium dynamics to separable states, thereby isolating the impact entanglement has on thermodynamic effects. Unlike thermodynamic entanglement measures, which signify a loose connection between entanglement and thermodynamic properties, imposing a constraint constitutes an active intervention into a system -- answering how much of a system's thermodynamics is caused by (not correlated with) its quantumness. We benchmark our theory by applying the constrained dynamics to several multipartite systems, including quantum batteries and quantum refrigerators.
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Abstract A thermodynamic theory of quantum entanglement as well as the establishment of rigorous formal connections between the laws of thermodynamics and the phenomenology of entanglement are currently open areas of investigation. In this quest, a core problem is embodied by the understanding of the role that entanglement plays in processes of work extraction. Here, by considering information thermodynamics-based protocols, we answer the question “Is it possible to infer, quantitatively, quantum correlations by considering work-extraction schemes?”. Our experimental settings consist of suitably designed multi-photon optical interferometers able to address the case of both bipartite and multipartite entangled states. We compare the performance of such criteria to that of witnesses of entanglement based on the violation of Bell-like tests, showing their inherently different nature. Our work contributes strongly to the ongoing efforts in establishing photonic systems as a platform for experiments in information thermodynamics.
We investigate the thermodynamic constraints on the pivotal task of entanglement generation using out-of-equilibrium states through a model-independent framework with minimal assumptions. We establish a necessary and sufficient condition for a thermal process to generate bipartite qubit entanglement, starting from an initially separable state. Consequently, we identify the set of system states that cannot be entangled, when no external work is invested. In the regime of infinite temperature, we analytically construct this set; while for finite temperature, we provide a simple criterion to verify whether any given initial state is or is not entangleable. Furthermore, we provide an explicit construction of the future thermal cone of entanglement—the set of entangled states that a given separable state can thermodynamically evolve to. We offer a detailed discussion on the properties of this cone, focusing on the interplay between entanglement and its volumetric properties. We conclude with several key remarks on the generation of entanglement beyond two-qubit systems, and discuss its dynamics in the presence of dissipation. Published by the American Physical Society 2024