Superconducting quantum circuits are 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. \textbf{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 non-trace-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.
@article{arxiv.1703.06613,
title = {Solving Systems of Linear Equations with a Superconducting Quantum Processor},
author = {Yarui Zheng and Chao Song and Ming-Cheng Chen and Benxiang Xia and Wuxin Liu and Qiujiang Guo and Libo Zhang and Da Xu and Hui Deng and Keqiang Huang and Yulin Wu and Zhiguang Yan and Dongning Zheng and Li Lu and Jian-Wei Pan and H. Wang and Chao-Yang Lu and Xiaobo Zhu},
journal= {arXiv preprint arXiv:1703.06613},
year = {2017}
}