Beamforming is conventionally understood as a collective property of many discrete antenna elements in both communication and radar fields, which links angular selectivity to array size, element spacing, and band-specific hardware. Here we uncover a fundamentally different beamforming mechanism achieved by a Rydberg atomic receiver: a Rydberg-atom vapor cell dressed by a local-oscillator field constitutes a continuous quantum aperture. In this regime, spatially-varying quantum coherence across the aperture provides continuous amplitude-phase control, allowing a directional beam pattern to emerge from one sensing volume rather than from an engineered array. We establish the theory of continuous quantum aperture and show that tailoring the local-oscillator field can directly program the aperture response. This enables reconfigurable single-peak, multipeak, and multiband beamforming within a single vapor cell. Experiments on a Rydberg atomic receiver prototype verify that practical beam patterns agree with theoretical predictions across aperture sizes, frequency bands, and local-oscillator configurations. Leveraging this new beamforming mechanism, we further demonstrate interference mitigation, multiuser access, and multiband multiuser access with the single-vapor-cell platform. Our results identify the continuous quantum aperture as a new operating principle of Rydberg atomic receivers and establish single-vapor-cell beamforming as an integrated and reconfigurable platform for spatially selective electromagnetic reception.
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This paper introduces the concept of continuous quantum aperture, in which a continuous atomic medium (a single Rydberg-atom vapor cell) performs efficient and reconfigurable beamforming
Beamforming is conventionally understood as a collective property of many discrete antenna elements in both communication and radar fields, which links angular selectivity to array size, element spacing, and band-specific hardware. Here we uncover a fundamentally different beamforming mechanism achieved by a Rydberg atomic receiver: a Rydberg-atom vapor cell dressed by a local-oscillator field constitutes a continuous quantum aperture. In this regime, spatially-varying quantum coherence across the aperture provides continuous amplitude-phase control, allowing a directional beam pattern to emerge from one sensing volume rather than from an engineered array. We establish the theory of continuous quantum aperture and show that tailoring the local-oscillator field can directly program the aperture response. This enables reconfigurable single-peak, multipeak, and multiband beamforming within a single vapor cell. Experiments on a Rydberg atomic receiver prototype verify that practical beam patterns agree with theoretical predictions across aperture sizes, frequency bands, and local-oscillator configurations. Leveraging this new beamforming mechanism, we further demonstrate interference mitigation, multiuser access, and multiband multiuser access with the single-vapor-cell platform. Our results identify the continuous quantum aperture as a new operating principle of Rydberg atomic receivers and establish single-vapor-cell beamforming as an integrated and reconfigurable platform for spatially selective electromagnetic reception.
Leveraging the quantum advantages of highly excited atoms, Rydberg atomic receivers (RAREs) represent a paradigm shift in microwave detection with extremely high sensitivity and broadband tunability. However, existing studies often model RAREs as isotropic point receivers and neglect the spatial variation of Rydberg atomic states within vapor cells, which can lead to inaccurate characterization of their reception patterns. To address this issue, we theoretically analyze the spatial response of a local-oscillator (LO) field-dressed RARE. Our results reveal that as the vapor-cell length increases, a receiving beam aligned with the LO field is formed, and its beamwidth is inversely proportional to the cell length. This finding enables atomic beamforming with only a single atomic vapor cell to enhance signal-to-noise ratio. Furthermore, we analyze the maximum beamforming gain of a single vapor cell by balancing the fundamental tradeoff between improved spatial selectivity and increased laser attenuation in the atomic medium as the vapor cell length becomes longer. To mitigate the beamforming-gain loss caused by laser attenuation, we further propose a segmental-vapor-cell architecture. In this architecture, multiple short vapor cells are arranged along the optical propagation path and separated by clear-air gaps. This design effectively expands the reception aperture while keeping the total vapor-cell length, and hence attenuation loss, fixed. As a result, it achieves a narrower beamwidth and higher beamforming gain than a conventional single-vapor-cell receiver, as demonstrated by extensive numerical results.
Radio reception relies on antennas for the collection of electromagnetic fields carrying information, and receiver elements for demodulation and retrieval of the transmitted information. Here, we demonstrate an atom-based receiver for AM and FM microwave communication with a 3 dB bandwidth in the baseband of ~100 kHz that provides optical circuit-free field pickup, multiband carrier capability, and inherently high field sensitivity. The atom-based receiver exploits field-sensitive cesium Rydberg vapors in a centimeter-sized glass cell, and electromagnetically induced transparency, a quantum-optical effect, as a readout of baseband signals modulated onto carriers with frequencies ranging over four octaves, from C-band to Q-band. Receiver bandwidth, dynamic range and sideband suppression are characterized, and acquisition of audio waveforms of human vocals demonstrated. The atomic receiver is a valuable receiver technology because it does not require antenna structures and is resilient against electromagnetic interference, while affording multiband operation in a single compact receiving element.
Quantum sensing using Rydberg atoms offers unprecedented opportunities for next-generation radar systems, transcending classical limitations in miniaturization and spectral agility. Implementing this paradigm for radar sensing, this work proposes a quantum-enhanced radar reception architecture enabled by the emerging Rydberg atomic receiver, replacing conventional antenna-to-mixer chains with a centimeter-scale vapor cell. The proposed approach is based on electromagnetically induced transparency with the Autler-Townes splitting enabling direct RF-to-optical downconversion within the atomic medium via an external co-frequency reference. To circumvent the intrinsic bottleneck on instantaneous bandwidth of atomic receiver, we invoke a non-uniform stepped-frequency synthesis strategy combining coarse laser frequency tuning with fine AC-Stark shift compensation. Additionally, we establish a nonlinear response model of the Rydberg atomic homodyne receiver and propose a customized nonlinear compensation method that extends the linear dynamic range by over 7 dB. We develop a compressive sensing algorithm (CS-Rydberg) to suppress noise and mitigate the undersampling problem. Experimentally, we demonstrate a compact prototype achieving centimeter-level ranging precision (RMSE = 1.06 cm) within 1.6-1.9 m. By synthesizing GHz-bandwidth (2.6-3.6 GHz), resolvable target separations down to 15 cm are observed under controlled sparse scenarios. These results not only validate the feasibility of quantum sensing based on Rydberg atomic receivers but also underscore the architecture's inherent scalability: by harnessing the atoms' ultra-broad spectral response, the synthesized bandwidth can be extended well beyond the current range, enabling sub-centimeter resolution in future radar systems while preserving quantum-traceable calibration and a highly simplified front end.
This paper develops an optically movable Rydberg atomic quantum receiver (RAQR), in which the probe and coupling beams are steered within each vapor cell to dynamically reconfigure the effective radio-frequency (RF) sensing position without mechanical actuation. A closed-form equivalent baseband model is derived by separating the atomic transduction coefficient, optical steering phase, and cell-center array response into distinct factors and the accuracy of the resulting model is validated against numerical solutions of the Lindblad master equation. Based on the derived model, we reveal two complementary channel-shaping mechanisms, including intrinsic beam-pattern shaping through RF-to-optical transduction and per-cell phase control enabled by optical displacement. To further exploit these capabilities, a non-convex sum-rate maximization problem is formulated over the optical positions and local oscillator design and solved via an alternating optimization framework with analytical gradients. Simulation results validate the derived model and demonstrate substantial performance gains enabled by optical movability, highlighting its potential as a programmable receiver architecture for future wireless networks.
Quantum sensing using Rydberg atoms offers unprecedented opportunities for next-generation radar systems, transcending classical limitations in miniaturization and spectral agility. This work proposes a quantum-enhanced radar reception architecture that replaces conventional antenna-tomixer chains with a centimeter-scale vapor cell as a quantum radio frequency (RF) field sensor and mixer, enabling this paradigm for radar sensing. This approach is based on electromagnetically induced transparency, which uses Autler-Townes splitting to enable direct RF-to-optical downconversion within the atomic medium via an external co-frequency reference. To circumvent the range-resolution limitation imposed by the narrow instantaneous response of the atomic receiver, we adopt a stepped-frequency synthesis strategy involving the hybrid manipulation of Rydberg energy states. This strategy combines coarse laser frequency tuning with fine AC-Stark shift compensation. Additionally, we establish a nonlinear response model of the Rydberg atomic homodyne receiver and propose a customized nonlinear compensation method that extends the linear dynamic range by over 7 dB. We developed a compressive sensing-based algorithm (CS-Rydberg) to suppress noise and mitigate the undersampling problem. Experimentally, we demonstrate a compact prototype that achieves centimeter-level ranging precision (RMSE = 1.06 cm) within 1.6–1.9 m. By synthesizing a 1-GHz equivalent bandwidth via sparse stepped-frequency sampling over 2.6–3.6 GHz, we observe resolvable target separations down to 15 cm under controlled sparse scenarios. These results validate the feasibility of quantum sensing based on Rydberg atomic receivers and underscore the architecture’s scalability. By harnessing the atoms’ ultrabroad spectral response, the synthesized bandwidth can extend well beyond the current range. This enables sub-centimeter resolution in future radar systems while preserving quantum traceable calibration and a highly simplified front end.
In this paper, we propose a self-superheterodyne Rydberg uniform array receiver for satellite uplink communications, in which the Doppler shift naturally induced by satellite motion is exploited to generate the intermediate-frequency signal. We first develop a near-field local oscillator (LO) synthesis model and characterize the spatially varying LO electric field across the Rydberg vapor cells. Based on a vapor-cell-center approximation, a closed-form radio frequency (RF)-to-optical conversion is derived, establishing an explicit bridge between the incident satellite signal and the LO-induced cell-level response. The derived model reveals that the programmable LO serves as an analog-domain channel-shaping mechanism by controlling the cell-level transduction gain, phase response, and phase-matching behavior. Building upon this equivalent channel model, we formulate an LO design problem that maximizes the Shannon capacity of the effective channel, and develop an efficient optimization algorithm for the LO amplitudes and phases. Simulation results demonstrate that the vapor-cell transduction can reshape the effective channel, adjust the beam-pattern alignment, and moderately reduce the inter-user correlation under suitable LO configurations. Furthermore, the proposed LO design significantly improves the achievable capacity over benchmark schemes, offering a promising self-superheterodyne Rydberg architecture for future satellite communication systems.