题目： Reducing intrinsic decoherence in a superconducting

circuit by quantum error detection

时间： 2013年 9月 3日（星期二）上午 10:30 地点：频标楼四楼报告厅 主讲人：王浩华 教授 单位：浙江大学物理系

武汉物数所理论交叉学术交流系列报告(第六十七期 )

主讲人简历及所获荣誉：美国宾州州立大学物理系 博士 (2006)南开大学物理系 學士 (1999)

浙江大学物理系 教授 (2010/09 至今 )美国加州大学圣塔芭芭拉分校 博士后 (2007/01-2010/08)

中组部首批青年拔尖人才 (2012)国家自然科学基金优秀青年基金 (2012)浙江省千人计划 (2011)教育部新世纪人才计划 (2011)

摘要： Quantum coherence is one of the keys to quantum computing, but

it is fundamentally limited by interactions with the environment. New device designs and better materials have significantly reduced the level of intrinsic decoherence in e.g. superconducting qubits, and in addition quantum error correction codes are being developed, which can repair errors as they occur. Quantum error detection (QED) provides an alternative, albeit non-deterministic approach to handling errors, avoiding some of the complexity of full quantum error correction by simply rejecting errors when they are detected. QED has been predicted to significantly reduce the impact of energy relaxation in qubits, one of the dominant sources of error in superconducting quantum circuits. Here we demonstrate a QED protocol based on the idea of quantum un-collapsing, using this protocol to suppress energy relaxation due to the environment in a three-qubit superconducting circuit. We encode quantum information in a target qubit, and use the other two qubits as ancillae to detect and reject errors. Using this protocol, we demonstrate an improvement in the storage time of a quantum state by a factor of roughly three, at the cost of a reduced probability of success. This constitutes the first experimental reduction of the impact of intrinsic dissipation on superconducting qubits, using a quantum protocol that is widely applicable.

*Work in collaboration with UC Santa Barbara and UC Riverside

主办单位：武汉物数所理论与交叉研究部