We report on broad instantaneous bandwidth microwave spectrum analysis with hot Rb87 atoms in a microfabricated vapor cell in a large magnetic field gradient. The sensor is a MEMS atomic vapor cell filled with isotopically pure Rb87 and N2 buffer gas to localize the motion of the atoms. The microwave signals of interest are coupled through a coplanar waveguide to the cell, inducing spin-flip transitions between optically pumped ground states of the atoms. A static magnetic field with large gradient maps the frequency spectrum of the input microwave signals to a position-dependent spin-flip pattern on absorption images of the cell recorded with a laser beam onto a camera. In our proof-of-principle experiment, we demonstrate a microwave spectrum analyzer that has ≈1 GHz instantaneous bandwidth centered around 13 GHz, 3 MHz frequency resolution, 2 kHz refresh rate, and a −23 dBm single-tone microwave power detection limit in 1 s measurement time. A theoretical model is constructed to simulate the image signals by considering the processes of optical pumping, microwave interaction, diffusion of Rb87 atoms, and laser absorption. We expect to reach more than 25 GHz instantaneous bandwidth in an optimized setup, limited by the applied magnetic field gradient. Our demonstration offers a practical alternative to conventional microwave spectrum analyzers based on electronic heterodyne detection. Published by the American Physical Society 2024

中文翻译：

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带有微制造原子蒸气室的宽瞬时带宽微波光谱分析仪


我们报道了在大磁场梯度中微加工蒸汽室中使用热 Rb87 原子进行的宽瞬时带宽微波光谱分析。该传感器是一个 MEMS 原子蒸气室，其中填充有同位素纯 Rb87 和 N2 缓冲气体，用于定位原子的运动。感兴趣的微波信号通过共面波导耦合到单元，在原子的光泵浦基态之间感应自旋翻转跃迁。具有大梯度的静态磁场将输入微波信号的频谱映射到用激光束记录到相机上的细胞吸收图像上的位置相关自旋翻转模式。在我们的原理验证实验中，我们展示了一种微波频谱分析仪，它在 1 s 测量时间内具有以 13 GHz 为中心的 ≈1 GHz 瞬时带宽、3 MHz 频率分辨率、2 kHz 刷新率和 −23 dBm 单音微波功率检测限值。通过考虑光泵浦、微波相互作用、Rb87 原子扩散和激光吸收的过程，构建了模拟图像信号的理论模型。我们预计在优化设置中达到超过 25 GHz 的瞬时带宽，受施加的磁场梯度限制。我们的演示为基于电子外差检测的传统微波频谱分析仪提供了一种实用的替代方案。 美国物理学会 2024 年出版