Rydberg-based Direction-of-Arrival (DoA) estimation has been hampered by the complexity of receiver arrays and the single-target, narrow-band limitations of existing single-receiver methods. This paper introduces a novel approach that addresses these limitations. We demonstrate that by spatially resolving the fluorescence profile along the vapor cell, the multi-target problem can be effectively solved. Our approach hinges on the insight that by superimposing incoming signals with a strong local oscillator (LO), the complex atomic absorption pattern is linearized into a simple superposition of sinusoids. In this new representation, each spatial frequency uniquely and directly maps to the DoA of a target. This reduces the multi-target challenge into a spectral estimation problem, which we address using Prony's method. Our approach, termed Imaging-based Spectral Estimation (ISE), inherently supports multi-target detection and restores the full broadband capability of the sensor by removing the restrictive cell-length dependency. This development also shows potential for realizing multi-channel Rydberg receivers and the continuous-aperture sensing required for holographic multiple-input multiple-output (MIMO). We develop a comprehensive theoretical model, derive the Cramer-Rao Lower Bound (CRLB) as a performance benchmark, and present simulations validating the effectiveness of the approach to resolve multiple targets.

翻译：基于里德堡原子的波达方向估计技术长期以来受限于接收器阵列的复杂性，以及现有单接收器方法固有的单目标、窄带局限性。本文提出一种新方法以应对这些局限。我们证明，通过对蒸气室沿程的荧光分布进行空间分辨，可以有效解决多目标探测问题。该方法的核心在于：通过将入射信号与强本振信号叠加，可将复杂的原子吸收模式线性化为简单的正弦波叠加。在此新表征下，每个空间频率唯一且直接地映射至一个目标的波达方向，从而将多目标探测问题转化为谱估计问题，并采用Prony方法求解。这种称为"基于成像的谱估计"的方法，本质上支持多目标探测，并通过消除对腔长的限制性依赖，恢复了传感器的全宽带能力。该进展还显示出实现多通道里德堡接收器及全息多输入多输出技术所需连续孔径传感的潜力。我们建立了完整的理论模型，推导了作为性能基准的克拉美-罗下界，并通过仿真验证了该方法在分辨多目标方面的有效性。