Quantum Instruction Set Design for Performance

• Published in: Physical review letters Vol. 130; no. 7; p. 070601
• Main Authors: Huang, Cupjin, Wang, Tenghui, Wu, Feng, Ding, Dawei, Ye, Qi, Kong, Linghang, Zhang, Fang, Ni, Xiaotong, Song, Zhijun, Shi, Yaoyun, Zhao, Hui-Hai, Deng, Chunqing, Chen, Jianxin
• Format: Journal Article
• Language: English
• Published: United States 17-02-2023
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.130.070601

A quantum instruction set is where quantum hardware and software meet. We develop characterization and compilation techniques for non-Clifford gates to accurately evaluate its designs. Applying these techniques to our fluxonium processor, we show that replacing the iSWAP gate by its square root SQiSW leads to a significant performance boost at almost no cost. More precisely, on SQiSW we measure a gate fidelity of up to 99.72% and averaging at 99.31%, and realize Haar random two-qubit gates with an average fidelity of 96.38%. This is an average error reduction of 41% for the former and a 50% reduction for the latter compared to using iSWAP on the same processor.