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Application and quantum properties of superpositions of oppositely squeezed states

Hiroo Azuma1,*, William J. Munro2, and Kae Nemoto2,1

  • *Contact author: zuma@nii.ac.jp
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Phys. Rev. A 113, 063728 – Published 17 June, 2026

DOI: https://doi.org/10.1103/dhq3-wcd7

Abstract

We show that superpositions of oppositely squeezed states—non-Gaussian Schrödinger-cat-like states—exhibit enhanced nonclassical features and provide an entanglement advantage in the small-squeezing regime. These states possess photon-number structures distinct from conventional coherent-state cat states, and we analyze their Wigner functions and the entanglement generated when they are injected into a 50:50 beam splitter. As a practical application, we demonstrate that they enable a high-quality heralded single-photon source whose second-order intensity correlation function is smaller than that obtained from a pure two-mode squeezed vacuum state. We further propose a linear-optical heralding scheme that approximates these superpositions without requiring strong Kerr nonlinearities. Our results indicate that the superposition of oppositely squeezed states is a promising non-Gaussian resource for quantum information processing, particularly for single-photon generation.

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Phys. Rev. A 113, 063728– Published 17 June, 2026
  • Received 5 November 2025
  • Accepted 28 May 2026
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