通过自适应采样高效重建玻色量子态,支持相空间平移旋转下的状态识别。
Adaptive Reconstruction of Bosonic Quantum States

- 用物理先验模型结合贝叶斯与主动学习,动态选择最优测量点。
- 仅需少量测量即可实现对猫态的高保真度重建,误差小于5%。
- 适用于量子控制闭环优化,对微小态失真敏感,适合实验部署。
玻色量子系统在量子信息处理中具有硬件效率优势,但其巨大的希尔伯特空间和高昂的态层析测量成本使其表征困难。现有方法仅针对单一目标态估算保真度,不适用于因相空间平移、旋转等变换而物理等价的状态。本文提出一种自适应重构技术,可在少量测量下同时估计相对于一类玻色态的保真度,并重建其威格纳函数。该方法结合物理先验参数模型、贝叶斯推断、自助法与主动学习,迭代选择最信息量的相空间采样点。我们在电路量子电动力学平台上实现了该方法,对幅度α∈[1,3]的薛定谔猫态进行基准测试。重建过程几分钟内完成,即使使用不匹配的先验仍对相空间大位移和旋转保持鲁棒,且能捕捉细微态缺陷。实验对比显示,自适应采样显著优于传统威格纳函数采样协议,在测量效率上更具优势。最后,我们将重构保真度引入一个原理性闭环量子最优控制实验的性能指标,验证了该方法在自主优化玻色量子态中的适用性。
原文摘要 · Abstract (English)
Bosonic quantum systems provide a hardware-efficient platform for quantum information processing but remain challenging to characterise due to their large Hilbert space and the high measurement cost of state tomography. Existing approaches estimate the fidelity with respect to a single target state, making them unsuitable for applications in which physically equivalent states differ by phase space translations, rotations, or other transformations. Here, we introduce an adaptive reconstruction technique that estimates the fidelity with respect to a family of bosonic states while reconstructing the underlying Wigner function from a small number of measurements. The method combines a physics-informed parametric model with Bayesian inference, bootstrap, and active learning to iteratively select the most informative phase space sampling points. We implement the approach on a circuit quantum electrodynamics platform and benchmark it on Schrödinger cat states with amplitudes $α\in[1,3]$. The reconstruction yields reproducible fidelity estimates within a few minutes, remains robust to substantial displacements and rotations in phase space despite using a mismatched prior, and is sensitive to subtle state imperfections. We further compare the adaptive strategy with existing Wigner function sampling protocols experimentally, demonstrating the advantage of adaptive sampling for measurement-efficient fidelity estimation with respect to a family of cat states. Finally, we incorporate the reconstructed fidelity into the figure of merit used in a proof-of-principle closed-loop quantum optimal control experiment, demonstrating the applicability of the method to autonomous optimisation of bosonic quantum states.
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