近日，日本东京理科大学的Yuta Shingu及其研究小组与日本国家先进工业科学技术研究所的Yuichiro Matsuzaki等人合作并取得一项新进展。经过不懈努力，他们提出误差缓解的量子退火方法。相关研究成果已于2024年4月2日在国际知名学术期刊《物理评论A》上发表。

本文提出了一种结合电磁方法的量子退火策略，即采用双态纯化来削弱退相干效应的影响。该方案由四个环节构成：常规动力学过程、单量子比特投影测量、与首个动力学过程相对应的哈密顿动力学逆映射以及测量数据的后处理。值得一提的是，该方案并不依赖需要脉冲操作的双量子比特门，因此它非常适合用于实际量子退火设备。此外，研究人员还进行了数值计算，结果显示，在估算退相干状态下的基态能量方面，他们的方案比传统的量子退火方法更为精确。

据悉，量子退火(QA)是制备问题哈密顿量基态的方法之一。在没有噪声的情况下，如果满足绝热条件，QA可以准确地估计基态能量。然而，在实践中，已知系统会受到退相干的影响。同时，人们对含噪中等尺度量子(NISQ)计算也进行了大量的研究。人们在实际的NISQ计算中，已经提出了许多减小噪声影响的误差缓解（EM）方法。

附：英文原文

Title: Quantum annealing with error mitigation

Author: Yuta Shingu, Tetsuro Nikuni, Shiro Kawabata, Yuichiro Matsuzaki

Issue&Volume: 2024/04/02

Abstract: Quantum annealing (QA) is one of the methods to prepare a ground state of a problem Hamiltonian. In the absence of noise, QA can accurately estimate the ground-state energy if the adiabatic condition is satisfied. However, in practice, systems are known to suffer from decoherence. Meanwhile, considerable research effort has been devoted to noisy intermediate-scale quantum (NISQ) computation. For practical NISQ computation, many error-mitigation (EM) methods have been proposed to mitigate the effects of noise. This paper proposes a QA strategy combined with an EM method, namely, dual-state purification, to suppress the effects of decoherence. Our protocol consists of four parts: the conventional dynamics, single-qubit projective measurements, the Hamiltonian dynamics corresponding to an inverse map of the first dynamics, and postprocessing of the measurement results. Importantly, our protocol works without two-qubit gates that require pulse operations; hence, it is suitable for devices designed for practical QA. In addition, we present numerical calculations to show that our protocol is more accurate than the conventional QA in estimating the ground-state energy under decoherence.

DOI: 10.1103/PhysRevA.109.042606

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.042606