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arXiv · 2508.13046

Quantum Phase Estimation Beyond the Gaussian Limit

Kimin Park·Tanjung Krisnanda·Yvonne Gao·Radim Filip
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Abstract

Quantum metrology aims to enhance measurement precision beyond the standard quantum limit (SQL), the benchmark set by classical resources, enabling advances in sensing, imaging, and fundamental physics. A critical milestone beyond the SQL is surpassing the Gaussian bound -- the fundamental precision limit achievable with any Gaussian state, such as optimally squeezed states. Certain non-Gaussian states, specifically asymmetric superpositions of coherent states (SCS) and superpositions of a vacuum and a Fock state (ON states), can outperform this Gaussian bound within an intermediate energy range. In particular, asymmetric SCS emerge as a highly practical resource for near-term quantum sensing architectures operating beyond the Gaussian limit due to their efficient preparation and processing via a constant-complexity protocol. Our comprehensive analysis under realistic loss, noise, and detection schemes quantifies the critical trade-off between achievable precision and the operational range of the non-Gaussian advantage. This work sheds light on the fundamental impact of non-Gaussianity and asymmetry on metrological tasks, and offers insights on how to leverage such resources in realistic near-term quantum enhanced sensors beyond the Gaussian limit.

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Kimin Park, Tanjung Krisnanda, Yvonne Gao, Radim Filip. 2025-08-18. Quantum Phase Estimation Beyond the Gaussian Limit. https://arxiv.org/abs/2508.13046

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