Microwave and Terahertz Field Sensing and Imaging using Rydberg Atoms

微波和太赫兹技术在现代生活中发挥着关键作用。微波是移动的和卫星通信的基础，也被用于导航和气象学中的雷达。在更高的频率下，太赫兹技术用于执行化学传感，非侵入性成像，状态监测等。这些应用和其他应用需要提供高灵敏度和执行空间分辨成像的能力的快速检测器，这在太赫兹领域尤其具有挑战性，因为大多数探测器需要低温冷却，并且在有限的绝对精度下提供缓慢的热响应时间。该传感器利用高度激发的里德堡原子的极端灵敏度，作为天线，在微波和太赫兹频率范围内提供精确的电场测量。利用激光激发热蒸气室中的里德伯原子，可以从弱探测光束传输中产生的扰动测量射频场。即（i）它们通过将原子特性与SI单位相关联而被固有地校准以提供完全的测量可追溯性，（2）用作用于现场测量的点状天线，以及（3）可以被光学探测以实现所研究的射频场的亚波长分辨率。拟议的研究计划将探索实施基于里德伯原子的电场传感器的一些关键挑战，包括优化电池材料和几何形状，以最大限度地减少对所施加电场的扰动或抑制，并开发测量技术以实现灵敏度和准确度的基本限制。为了应对这些挑战，我们将结合联合收割机英国的专业知识，包括里德堡原子光学探测的先驱，制造和封装与微波和太赫兹测量兼容的原子蒸气室，并展示结构化射频场的精确场测量和2D成像。为了验证设备的准确性，我们将比较我们的传感器的性能与国家物理实验室最先进的校准参考。最后，我们将展示传感器在现实世界中的应用，包括类似于WiFi的全光微波通信方案和太赫兹天线阵列的复杂近场发射特性。这些传感器为射频传感、成像和计量提供了一种新的方法，并提供了一种在微波频率下实现增强灵敏度的途径，同时为太赫兹领域的新兴应用提供了一种使能技术。

Microwave and terahertz technologies play a critical role in modern life. Microwaves underpin mobile and satellite communications and are used for radar in navigation and meteorology. At higher frequencies, terahertz technologies are used to perform chemical sensing, non-invasive imaging, condition monitoring and more. These applications, and others, require fast detectors offering high sensitivity and the ability to perform spatially resolved imaging, which is particularly challenging in the terahertz domain where the majority of detectors require cryogenic cooling and offer slow thermal response times with limited absolute accuracy.In this proposal we seek to address this technology gap by developing a new class of atom-based sensors that exploit the extreme sensitivity of highly-excited Rydberg atoms which act as antennae to provide precision electric field measurement across the microwave and terahertz frequency range. Using lasers to excite Rydberg atoms in a thermal vapour cell, the radio-frequency fields can be measured from the resulting perturbation in the transmission of a weak probe beam.Atom-based sensors provide a number of advantages over traditional electric field measurement techniques; namely (i) they are intrinsically calibrated by relating the atomic properties to SI units to provide full measurement traceability, (2) act as point-like antenna for an in-situ measurement of the field, and (3) can be optically probed to enable sub-wavelength resolution of the radio-frequency field under study. The proposed research programme will explore a number of key challenges to implementing Rydberg-atom-based electric field sensors, including optimising the cell materials and geometry to minimise the perturbation or suppression of the applied field and developing measurement techniques to achieve the fundamental limits of sensitivity and accuracy. To address these challenges we will combine UK based expertise, including the pioneers of optical detection of Rydberg atoms, to fabricate and characterise atomic vapour cells compatible with microwave and terahertz measurements and demonstrate precision field measurement and 2D imaging of structured radio-frequency fields. To verify the device accuracy we will compare the performance of our sensors to state-of-the-art calibrated references at the National Physical Laboratory. Finally, we will demonstrate real-world application of the sensors to areas including all-optical microwave communication schemes similar to WiFi and characterisation of the complex near-field emission from a terahertz antenna array. These sensors offer a new approach to radiofrequency sensing, imaging and metrology and provide a route to achieving enhanced sensitivity at microwave frequencies whilst providing an enabling technology for emerging applications in the terahertz domain.