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arXiv · 2607.17023

Rigorous characterization of continuous-variable quantum states via optical parametric amplifiers

Manthan Badbaria·Fumiya Hanamura·Maxime Garnier·Ulysse Chabaud·Rajveer Nehra
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Abstract

Characterizing non-Gaussian quantum states is of paramount importance for continuous-variable quantum information processing, yet conventional homodyne-measurement-based state tomography remains limited by optical loss, detector efficiency, and measurement bandwidth. Here, we introduce an integrated framework for loss-tolerant characterization and certification using high-gain phase-sensitive optical parametric amplification and power measurements. Our computationally efficient semidefinite programming approach enables faithful reconstruction of parity-symmetric quantum states from amplified quadrature measurements while substantially relaxing detector-efficiency requirements and increasing the measurement bandwidth. We further develop a certification framework that directly quantifies non-Gaussianity via stellar-rank witnesses and Wigner negativity, using the same quadrature-power measurements. We demonstrate the efficacy of the proposed framework through both simulated and experimental data for representative quantum states, including single-photon, Schrodinger cat, and Gottesman-Kitaev-Preskill (GKP) states. By unifying loss-tolerant measurements, state tomography, and nonclassical-state certification within a single experimentally accessible framework, our approach provides a practical pathway toward verifying increasingly complex states and can be readily implemented with current quantum photonic technologies.

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Manthan Badbaria, Fumiya Hanamura, Maxime Garnier, Ulysse Chabaud, Rajveer Nehra. 2026-07-19. Rigorous characterization of continuous-variable quantum states via optical parametric amplifiers. https://arxiv.org/abs/2607.17023

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