Solving Systems of Linear Equations with a Superconducting Quantum Processor

Date: 2017-05-26
Authors Yarui Zheng, Chao Song, Ming-Cheng Chen, Benxiang Xia, Wuxin Liu, Qiujiang Guo, Libo Zhang, Da Xu, Hui Deng, Keqiang Huang, Yulin Wu, Zhiguang Yan, Dongning Zheng, Li Lu, Jian-Wei Pan, H. Wang, Chao-Yang Lu, and Xiaobo Zhu
Journal No. Phys. Rev. Lett. 118, 210504
Abstract Superconducting quantum circuits are a promising candidate for building scalable quantum computers. Here, we use a four-qubit superconducting quantum processor to solve a two-dimensional system of linear equations based on a quantum algorithm proposed by Harrow, Hassidim, and Lloyd [Phys. Rev. Lett. 103, 150502 (2009)], which promises an exponential speedup over classical algorithms under certain circumstances. We benchmark the solver with quantum inputs and outputs, and characterize it by nontrace-preserving quantum process tomography, which yields a process fidelity of 0.837±0.006. Our results highlight the potential of superconducting quantum circuits for applications in solving large-scale linear systems, a ubiquitous task in science and engineering.