论文标题

使用基本增强的机器重建量子状态

Reconstructing Quantum States Using Basis-Enhanced Born Machines

论文作者

Gomez, Abigail McClain, Yelin, Susanne F., Najafi, Khadijeh

论文摘要

量子硬件的快速改进为复杂问题打开了大门,但是量子系统本身的精确表征仍然是一个挑战。为了解决这一障碍,已经开发出了采用生成机器学习模型的新型断层扫描方案,从而从有限的经典数据中实现了量子状态重建。特别是,量子启发的机器提供了一种自然的方式,将测量数据编码为量子状态的模型。出生的机器在从古典数据中学习方面取得了巨大的成功。但是,迄今为止,天生机器从量子测量中学习的全部潜力尚未实现。为此,我们设计了一个复杂的基础增强机器,并表明它可以使用仅两个Pauli测量基础的投影测量值重建纯量子状态。我们实施了基础增强的机器,以在1D链条原子的整个相图上学习基础状态,以有序的阶段甚至在量子忠诚度达到99%的关键点,重建量子状态深处。该模型准确地预测了量子相关性和不同的可观察力,并且考虑了37吨的系统大小。使用此方案成功重建了一维XY自旋链的相位图的量子状态。我们的方法仅需要简单的Pauli测量值,其样品复杂性随系统大小四倍地缩放,使其适合实验实现。

Rapid improvement in quantum hardware has opened the door to complex problems, but the precise characterization of quantum systems itself remains a challenge. To address this obstacle, novel tomography schemes have been developed that employ generative machine learning models, enabling quantum state reconstruction from limited classical data. In particular, quantum-inspired Born machines provide a natural way to encode measured data into a model of a quantum state. Born machines have shown great success in learning from classical data; however, the full potential of a Born machine in learning from quantum measurement has thus far been unrealized. To this end, we devise a complex-valued basis-enhanced Born machine and show that it can reconstruct pure quantum states using projective measurements from only two Pauli measurement bases. We implement the basis-enhanced Born machine to learn the ground states across the phase diagram of a 1D chain of Rydberg atoms, reconstructing quantum states deep in ordered phases and even at critical points with quantum fidelities surpassing 99%. The model accurately predicts quantum correlations and different observables, and system sizes as large as 37 qubits are considered. Quantum states across the phase diagram of a 1D XY spin chain are also successfully reconstructed using this scheme. Our method only requires simple Pauli measurements with a sample complexity that scales quadratically with system size, making it amenable to experimental implementation.

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