An outstanding challenge of quantum computing is to build quantum devices with both excellent coherence and reliable universal control . Ancilla systems are often indispensable to universal control of a nearly isolated quantum system. However, ancilla systems are typically more vulnerable to environmental noise, which limits the performance of such ancilla-assisted quantum control. To address this challenge of ancilla-induced decoherence, we propose a general framework that integrates quantum control and quantum error correction , so that robust quantum gates resilient to ancilla noise can be achieved. We introduce the path independence criterion for fault-tolerant quantum gates against ancilla errors. As an example, we provide a path-independent gate for superconducting circuits with a hardware-efficient design, which has recently been experimentally implemented .
References: 1. W. -L. Ma, S. Puri, R. J. Schoelkopf et al., Sci. Bull. 66, 1789 (2021).
2. W. -L. Ma, M. Zhang, Y. Wong et al., Phys. Rev. Lett. 125, 110503 (2020).
3. P. Reinhold, S. Rosenblum, W. -L. Ma et al., Nat. Phys. 16, 822 (2020).
Wen-Long Ma is currently an associate professor at Institute of Semiconductors (IOS), Chinese Academy of Sciences (CAS). He got his Ph.D. degree from IOS, CAS (2015). He was a postdoctoral fellow at the Chinese University of Hong Kong (2015–2017), Yale University (2017–2019) and University of Chicago (2019–2020). His research interest includes quantum decoherence, quantum sensing, quantum control, quantum error correction and fault-tolerant quantum computation. He has published 18 papers in journals including Nature Physics, Nature Communications, PRL and PRA/B/Applied.