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arXiv:2601.16698 · Physical Review Research

Entanglement harvesting in the presence of cavities

Jannik Ströhle, Nikolija Momcilovic

quant-phSubmitted Jan 23, 2026• Announced Jan 26, 2026• 1 citation
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Abstract

So far, entanglement harvesting has been extensively studied in free space setups. Here, we provide a detailed analytical and numerical analysis of entanglement harvesting in cavities. Specifically, we adiabatically couple the quantized electromagnetic field to two identical Gaussian detectors located on the symmetry axis of a cylindrical cavity. Our numerical investigations reveal a strong dependence on the cavity length, while showing invariance under changes in the cavity radius in regimes of maximal entanglement. Moreover, we identify different scalings of the detector system parameters for entanglement inside and outside the light cone. Finally, we uncover a strong dependence of the harvested correlations on the cavity induced parity of the electromagnetic field.

Comments
17 pages, 6 Figures

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So far, entanglement harvesting has been extensively studied in free space setups. Here, we provide a detailed analytical and numerical analysis of entanglement harvesting in cavities. Specifically, we adiabatically couple the quantized electromagnetic field to two identical Gaussian detectors located on the symmetry axis of a cylindrical cavity. Our numerical investigations reveal a strong dependence on the cavity length, while showing invariance under changes in the cavity radius in regimes of maximal entanglement. Moreover, we identify different scalings of the detector system parameters for entanglement inside and outside the light cone. Finally, we uncover a strong dependence of the harvested correlations on the cavity induced parity of the electromagnetic field.
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Entanglement harvesting provides an operational means of probing the nonlocal correlation structure of quantum fields through localized detector-field interactions. Although harvesting has been investigated in a wide variety of spacetime backgrounds and quantum field states, existing studies largely focus on individual detector configurations or specific physical settings. In this work, we develop a unified perturbative framework for entanglement harvesting with localized Unruh-DeWitt detectors that is applicable to arbitrary detector trajectories and quantum field states through the corresponding Wightman function. By expressing the detector response in terms of dimensionless variables and analytically reducing the perturbative integrals to numerically efficient representations, the framework enables a systematic exploration of multidimensional harvesting landscapes, phase boundaries, and harvesting robustness. As representative applications, we investigate inertial detectors in the Minkowski vacuum, thermal field states, and uniformly accelerated observers. We show that finite temperature enhances both the local detector response and the nonlocal exchange amplitude, leading, within the perturbative Gaussian-switching framework considered here, to an enlargement of the harvesting region in parameter space. The resulting harvesting landscapes provide a global characterization of detector-field interactions and demonstrate how temperature and observer motion reshape the competition between local detector noise and nonlocal field correlations. The framework developed here provides a unified and readily extensible methodology for investigating entanglement harvesting across a broad class of relativistic quantum systems.
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