能量不足：变分量子本征求解器的泄漏感知拟设准则
Energy Is Not Enough: Leakage-Aware Ansatz Criterion for Variational Quantum Eigensolvers
- University of Delaware（特拉华大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
针对VQE中仅凭能量无法验证态有效性的问题，提出结合投影扇区误差、泄漏和参数数的拟设评估准则，实验表明UCC型拟设消除泄漏但不保证精度，并给出噪声下的诊断框架。
AI中文摘要：
在固定电子数扇区的分子变分量子本征求解器（VQE）计算中，仅凭投影扇区能量并不能证明所制备态在物理上是有效的。我们证明，一个态可以具有零投影扇区误差，而其几乎所有的概率质量都位于目标粒子数扇区之外。因此，我们使用三个量来评估拟设族：投影扇区误差、物理扇区之外的泄漏以及参数数量。我们的无噪声实验表明，粒子数保持的UCC型拟设族消除了由拟设引起的泄漏，但并不保证基态精度。在参数预算比较实验中，一次性排序规则选择相同的生成器序列并产生相同的误差。自适应混合程序在选定的预算下实现了更低的平均投影扇区误差。利用已有的Kraus不变子空间准则，我们还通过正算子表达信道引起的泄漏，并解析地讨论全局和局部去极化噪声。这为超越能量比较拟设提供了一个实用的诊断框架。
英文摘要：
In molecular variational quantum eigensolver (VQE) calculations for a fixed electron-number sector, the projected-sector energy alone does not certify that a prepared state is physically valid. We show that a state can have zero projected-sector error while almost all of its probability mass lies outside the target particle-number sector. We therefore evaluate ansatz families using three quantities: projected-sector error, leakage outside the physical sector and parameter count. Our noiseless experiments show that particle-preserving UCC-style families eliminate leakage induced by ansatze, but do not guarantee ground-state accuracy. In the parameter-budget comparison experiments, the one-shot ranking rules select identical generator sequences and yield identical errors. The adaptive hybrid procedure achieves lower mean projected-sector errors at selected budgets. Using established Kraus invariant-subspace criteria, we also express channel-induced leakage through a positive operator and discuss global and local depolarizing noise analytically. This gives a practical diagnostic framework for comparing ansatze beyond energy alone.
