论文标题
从本地测量中学习全球费用的过渡性过渡
Transitions in the learnability of global charges from local measurements
论文作者
论文摘要
我们考虑以全球保守的费用监视量子系统，并询问观察者（“窃听”）如何从本地投影测量值中学习此类系统的全球费用。我们发现相变为测量率的函数，具体取决于有关窃听器访问的量子动力学的多少信息。对于与U（1）对称性的随机统一电路，我们提出了仅从局部测量结果中重建全局电荷的最佳经典分类器。我们证明了该分类器在热力学极限中的性能中存在相变的存在。我们还通过包括一些有关统一大门模式的知识来研究数值改进的分类器。
We consider monitored quantum systems with a global conserved charge, and ask how efficiently an observer ("eavesdropper") can learn the global charge of such systems from local projective measurements. We find phase transitions as a function of the measurement rate, depending on how much information about the quantum dynamics the eavesdropper has access to. For random unitary circuits with U(1) symmetry, we present an optimal classical classifier to reconstruct the global charge from local measurement outcomes only. We demonstrate the existence of phase transitions in the performance of this classifier in the thermodynamic limit. We also study numerically improved classifiers by including some knowledge about the unitary gates pattern.
