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  • Letter
  • Open Access

Continuous variable entanglement in a cold-atom mirrorless optical parametric oscillator

G. C. Borba1,2, R. S. N. Moreira1,3, L. S. Cruz4, M. Martinelli2, D. Felinto1, and J. W. R. Tabosa1,*

  • *Contact author: jose.tabosa@ufpe.br
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Phys. Rev. Research 8, L012006 – Published 9 January, 2026

DOI: https://doi.org/10.1103/k6z4-816x

Abstract

In this work, we explore both the internal and external atomic degrees of freedom to observe quantum entanglement between the modes produced by a mirrorless optical parametric oscillator operating below the oscillation threshold in a sample of free-space cold cesium atoms. Using a new heterodyne technique, we recover the covariance matrix that reveals the quantum entanglement for two different pairs of modes, thus demonstrating the generation of four entangled modes in this system. Applications to quantum networks and the possibilities of studying higher orders of entanglement are a direct consequence of the present study.

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Phys. Rev. Research 8, L012006– Published 9 January, 2026
  • Received 24 December 2024
  • Revised 8 October 2025
  • Accepted 15 December 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.

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