Leveraging the quantum advantages of highly excited atoms, Rydberg atomic receivers (RAREs) represent a paradigm shift in radio wave detection, offering high sensitivity and broadband reception. However, existing studies largely model RAREs as isotropic point receivers and overlook the spatial variations of atomic quantum states within vapor cells, thus inaccurately characterizing their reception patterns. To address this issue, we present a theoretical analysis of the aforementioned spatial responses of a standard local-oscillator (LO)- dressed RARE. Our results reveal that increasing the vapor-cell length produces a receive beam aligned with the LO field, with a beamwidth inversely proportional to the cell length. This finding enables atomic beamforming to enhance received signal-to-noise ratio using only a single-antenna RARE. Furthermore, we derive the achievable beamforming gain by characterizing and balancing the fundamental tradeoff between the effects of increasing the vapor cell length and the exponential power decay of laser propagating through the cell. To overcome the limitation imposed by exponential decay, we propose a novel RARE architecture termed segmental vapor cell. This architecture consists of vapor-cell segments separated by clear-air gaps, allowing the total cell length (and hence propagation loss) to remain fixed while the effective cell length increases. As a result, this segmented design expands the effective atom-field interaction area without increasing the total vapor cell length, yielding a narrower beamwidth and thus higher beamforming gain as compared with a traditional continuous vapor cell.

翻译：利用高激发态原子的量子优势，里德堡原子接收器（RAREs）代表了无线电波检测范式的转变，具有高灵敏度和宽带接收能力。然而，现有研究大多将RAREs建模为各向同性的点接收器，忽略了蒸气室内原子量子态的空间变化，从而不准确地表征了其接收模式。为解决这一问题，我们对标准本地振荡器（LO）修饰的RARE的上述空间响应进行了理论分析。我们的结果表明，增加蒸气室长度会产生一个与LO场对齐的接收波束，其波束宽度与室长成反比。这一发现使得仅使用单天线RARE即可通过原子波束成形来提高接收信噪比。此外，我们通过表征并权衡增加蒸气室长度与激光在室内传播的指数功率衰减之间的基本权衡，推导出了可实现的波束成形增益。为克服指数衰减带来的限制，我们提出了一种称为分段蒸气室的新型RARE架构。该架构由被空气间隙分隔的蒸气室段组成，使得总室长（以及相应的传播损耗）保持不变，而有效室长得以增加。因此，与传统的连续蒸气室相比，这种分段设计在不增加总蒸气室长度的前提下扩展了有效的原子-场相互作用区域，从而产生更窄的波束宽度和更高的波束成形增益。