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Absence of entanglement growth in Dicke superradiance

N. S. Bassler

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Phys. Rev. A 112, 053713 – Published 13 November, 2025

DOI: https://doi.org/10.1103/qxx1-xr44

Abstract

Dicke superradiance describes an ensemble of N permutationally invariant two-level systems collectively emitting radiation with a peak radiated intensity scaling as N2. Individual Dicke states are typically entangled. However, the density matrix during superradiant decay is a mixture of such states, raising the subtle question of whether the total state is entangled or separable. We resolve this by showing analytically that for any N, starting from the fully excited state, the collective decay preserves separability for all times. This answers a longstanding question on the role of entanglement in Dicke superradiance and underscores that, despite collective dissipation, separable states remain separable under these dynamics.

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Phys. Rev. A 112, 053713– Published 13 November, 2025
  • Received 29 April 2025
  • Revised 21 July 2025
  • Accepted 10 October 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by Max Planck Society.

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