内容摘要：Quantum metrology pursues the realization of higher-precision measurements to physical quantities than the classically achievable limits by exploiting quantum features, such as quantum entanglement and squeezing, as resources. It has potential application in developing next-generation frequency standard, magnetometer, radar, and navigation. However, the ubiquitous decoherence in quantum world degrades the quantum resources and forces the precision not only to reduce to the classical shot-noise limit at an optimal encoding time but also to become divergent in the long-time condition. This is called the no-go theorem of noisy quantum metrology and dramatically hinders its application. Therefore, how to realize the promised performance of quantum metrology in practice attracts much attention in recent years. In this talk, I will report our studies on overcoming the no-go theorem by Floquet engineering. It is found that, by applying a periodic driving on the atoms of the Ramsey-spectroscopy-based quantum metrology, the ultimate precision to measure their frequency returns to its ideal t-1 scaling with the encoding time whenever a Floquet bound state is formed by the system consisting of each driven atom and its local noise. Combining with the optimal control, this mechanism also makes the ideal Heisenberg-limit scaling completely recovered for arbitrary atom number N. Our result supplies an insightful instruction for experiment to implement quantum metrology in practical decoherence situation.

报告人简介：安钧鸿：2005年在兰州大学获博士学位并留校工作。2006年至2014年相继在台湾成功大学和新加坡国立大学从事博士后、研究员、访问研究员；2011年受聘为教授；2013年入选教育部新世纪优秀人才支持计划；2016年入选甘肃省飞天学者；2017年入选中央军委科技委国防科技创新特区主题专家组专家；2019年入选国家“万人计划”青年拔尖人才和中科院青年创新促进会特邀会员；2021年入选甘肃省领军人才；2025年入选教育部长江学者特聘教授。从事量子光学、量子精密测量、拓扑物态和量子热力学等理论物理基础问题研究。