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  • Open Access

Nonlinear squeezing of superpositions of quadrature eigenstates

Vojtěch Kuchař and Petr Marek

  • Department of Optics, Palacký University, 17. listopadu 1192/12, 779 00 Olomouc, Czech Republic

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Phys. Rev. A 112, 053706 – Published 7 November, 2025

DOI: https://doi.org/10.1103/nlkq-2r7l

Abstract

We introduce a family of operators exploiting the symmetry of superpositions of quadrature eigenstates (SQEs) and demonstrate how the associated nonlinear squeezing, quantified by the expectation value of such operators, serves both as a witness of non-Gaussianity and as an indicator of the quality of SQE approximations. To establish the usefulness of this measure, we connect it to quantum state fidelity and evaluate its implications in breeding protocols. Finally, we construct optimal approximations of SQE states in truncated Fock spaces.

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Phys. Rev. A 112, 053706– Published 7 November, 2025
  • Received 20 June 2025
  • Accepted 23 September 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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