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arXiv · 2605.23617

Multiphoton heralding generates large-amplitude squeezed Schr\"odinger cat states and parity-selective Fock superpositions from squeezed vacuum via an OPA

Yusuf Turek·Ming-Yan Sun·Xiao-Xi Yao
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Abstract

We propose a multiphoton heralding scheme using an optical parametric amplifier (OPA) that converts squeezed vacuum into two families of non-Gaussian states: large-amplitude squeezed Schr\"odinger cat states and low-order parity-selective Fock superpositions. By injecting m photons into the idler port and detecting n photons at the output, effective high-order photon subtraction is realized in a single OPA device. The heralded states exhibit strong Wigner negativity and high phase-space complexity. Remarkably, under photon loss, the complexity remains substantial even after negativity vanishes, indicating a loss-resilient quantum resource. These states also surpass the Heisenberg limit in phase estimation. Our protocol establishes the OPA as a versatile platform for generating non-Gaussian states, with promising applications in loss-resilient quantum metrology and fault-tolerant quantum information processing.

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Yusuf Turek, Ming-Yan Sun, Xiao-Xi Yao. 2026-05-22. Multiphoton heralding generates large-amplitude squeezed Schr\"odinger cat states and parity-selective Fock superpositions from squeezed vacuum via an OPA. https://arxiv.org/abs/2605.23617

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