基于里德堡原子量子相干效应的微波电场精密测量

Accurate electromagnetic field sensing is of great importance and necessity for exploring new materials, new electronic devices and for investigating new electromagnetic effects; however, conventional microwave E-field measurement techniques is unable to achieve high sensitivity, high spatial resolution and high accuracy, and cannot directly trace to SI units and basic physical constants. Thus the state of art is unable to satisfy the precision measurement requirement. The possibility of using Rydberg atom for microwave electrometry has been proved recently, as the Rydberg atom is very sensitive to incident microwave E-field; however, some key issues still need to be investigated to make theoretical research a real precision measurement capability. The investigation of coherent mechanism, characteristics, and operation of Rydberg atom in presence of microwave E-field, especially the phenomenon of Aulter-Townes (AT) splitting within Electromagnetically Induced Transparency (EIT) will be carried out; key issues of quantum sensor and measurement facility development, and measurement uncertainty evaluation will be focused. The purpose is to develop a novel solution which could make microwave E-field measurement be directly traceable to frequency (EIT-AT splitting) and Planck’s constant. Main work includes and will be carried out as follows. The first content is to investigate coherent features of microwave E-filed and Rydberg atom EIT, especially E-filed frequency, strength and polarization selective properties; since the presence of the vapor cell itself may affect the traceability of such an atom based E-field measurement, then the analysis of a vapor cell from an electric perturbing perspective will be conducted; finally we will evaluate the precision measurement capability using the national power flux density standard (standard E-field) and also measurement uncertainties. The main purpose is to realize the sensitivity of 10mV/m for 1 GHz ~ 110 GHz microwave E-field measurement, with less than 0.5% total measurement uncertainty, which is one order of magnitude improvement comparing with conventional solutions. This work is of major significance for developing theory basis and technology foundation for modern quantum-based microwave field metrology system in future.

电磁场的精确感知是探索新材料、新器件，探究新电磁效应的重要基础。现有微波电场测量手段无法实现高灵敏度、高分辨率和高准确度测量，并且无法将量值直接有效溯源至基本物理常数，远不能满足精密测量需求。里德堡原子已被证实可用于微波电场测量，但离形成精密测量能力尚有诸多问题亟待解决。本项目着重研究微波电场作用下里德堡原子量子相干机理、特性及操控，特别是电磁感应透明（EIT）产生的AT劈裂，研制量子传感器和电场精密测量装置，将微波电场有效溯源至频率（EIT-AT劈裂）和普朗克常数。主要内容包括：微波电场频率、幅度和极化对里德堡原子量子相干的影响机制；原子气室对微波电场的微扰动性研究；基于功率密度标准的精密测量验证及电场测量不确定度分析。预期对1GHz~110GHz电场实现灵敏度为10mV/m、不确定度优于0.5%的精密测量，比传统方法提高一个数量级，为建立基于量子理论的微波计量标准提供理论和技术基础。

国际单位制（SI）的重新定义的本质是将七个基本物理量通过宏观或微观量子效应定义到基本物理常数，从而更稳定、更准确地复现量值。研究可溯源至基本物理常数的微波精密测量是电磁计量的一个重要发展趋势。本项目围绕微波电场作用下里德堡原子量子相干机理、特性及操控，以及微波电场精密测量量子传感器电磁特性两大关键科学问题开展研究，为实现可溯源至普朗克常数的微波电场量子计量基准奠定技术基础。主要研究内容和重要进展概括如下：.（1）在微波电场作用下Rydberg原子量子相干作用机理研究方面，理论上进一步完善了微波电场作用下的四能级里德堡原子量子相干作用模型，开展了磁场作用下的Rydberg原子Zeeman超精细态光谱研究以及基于Mach-Zehnder干涉测量的里德堡原子EIT噪声转移特性研究。（2）在微波电场量子计量基准研制方面，攻克了多项量子光学实验操控技术，建立微波电场量子精密测量装置一套，完成了原子气室扰动等理论分析和实验研究，研制最小9mm×9mm×9mm原子气室以及一种新型的谐振对消新型原子气室，不断提升精密测量指标，实测8.35GHz~104.75GHz频段内典型频点灵敏度优于10mV/m，量子测量与理论计算偏差为0.5%~2%，典型频点10.22GHz场强测量标准不确定度初评结果为0.48%。（3）开展了基于量子基准的量值传递及量子传感应用研究，包括探索了基于微波电场强度和原子气体吸收光谱的非线性特性的一种空间时变电场量子测量新机制，并开展了原子接收机研究工作，实现亚波长空间高分辨微波电场成像，研究一种基于量子基准的天线参数测量新方法。.本项目探索了一种基于量子效应的微波电场量子感知和精密测量新原理方法，实现可直接溯源至普朗克常数的微波电场量子精密测量，是SI变革背景下的一次微波精密测量技术革新探索。相关研究工作受到国际国内专家关注和认可，累计在国内外进行应邀学术报告10余次，发表录用论文SCI/EI论文15篇；申请发明专利5项（其中授权1项），培养博士研究生1名，硕士研究生5名。