Abstract Rydberg atom-based time-receiving systems enable high-sensitivity demodulation of long-wave signals for precise one-pulse-per-second (1PPS) output, surpassing the limitations of conventional long-wave receivers. Here, we first report the theoretical and experimental demonstration of a nanosecond-jitter Rydberg time-receiving system for eLoran signals. We establish a novel theoretical model that quantitatively reveals the relationship between timing jitter and system parameters, exemplified by the DC Stark shift and the coupling-beam Rabi frequency. Experimentally, we first demonstrate 1PPS timing output based on an atomic system, achieving a root-mean-square (RMS) timing jitter of 27.90 ± 0.39 ns. Furthermore, we demonstrate the timing performance of our system across high-noise conditions and at low input signal amplitudes, validating its robustness under practical weak eLoran signal conditions. This work validates the feasibility of Rydberg atom-based architectures for high-precision ground-based timing and establishes a performance benchmark for next-generation atomic-optical positioning, navigation, and timing (PNT) systems.
Abstract Rydberg atom-based time-receiving systems enable high-sensitivity demodulation of long-wave signals for precise one-pulse-per-second (1PPS) output, surpassing the limitations of conventional long-wave receivers. Here, we first report the theoretical and experimental demonstration of a nanosecond-jitter Rydberg time-receiving system for eLoran signals. We establish a novel theoretical model that quantitatively reveals the relationship between timing jitter and system parameters, exemplified by the DC Stark shift and the coupling-beam Rabi frequency. Experimentally, we first demonstrate 1PPS timing output based on an atomic system, achieving a root-mean-square (RMS) timing jitter of 27.90 ± 0.39 ns. Furthermore, we demonstrate the timing performance of our system across high-noise conditions and at low input signal amplitudes, validating its robustness under practical weak eLoran signal conditions. This work validates the feasibility of Rydberg atom-based architectures for high-precision ground-based timing and establishes a performance benchmark for next-generation atomic-optical positioning, navigation, and timing (PNT) systems.
Superdirective receive arrays, whose gain can exceed that of traditional antenna arrays, have been historically challenging to realize due to high sensitivity to white noise, strong mutual coupling, and the complexity of designing receive matching networks in conventional systems. This paper proposes and analyzes a novel superdirective receiver architecture based on an array of Rydberg atomic sensors to overcome these fundamental limitations. By leveraging the quantum properties of Rydberg atoms, the proposed receiver is inherently immune to the internal thermal noise that plagues traditional receivers. As a result, the system performance is primarily limited by external background noise and fundamental quantum noise. We develop a comprehensive signal and noise model and the-oretically derive the upper bound on the directivity gain for the proposed Rydberg-based receiver. Furthermore, we prove that for multi-user scenarios, the effective channel vectors for different users become asymptotically orthogonal as the number of sensors approaches infinity, enabling high-capacity spatial multiplexing even with deep sub-wavelength element spacing. Extensive simulations demonstrate the superior performance of the proposed system over traditional superdirective receivers and validate our theoretical findings. The results highlight Rydberg atomic arrays as a promising technology for developing ultra-sensitive, compact, and broadband superdirective receivers for next-generation communication and sensing applications.
Rydberg atoms are atoms in their highly excited energy states. The physical properties of Rydberg atoms in the presence of external fields play an important role in quantum precision measurement. In recent years, radio-frequency electric field sensing based on Rydberg atoms has attracted significant interest. It is widely recognized as an electromagnetic sensing system fundamentally different from traditional ones. As a quantum sensor, it is expected to surpass several foundational limitations of traditional receivers, such as sensitivity, dynamic range and frequency bandwidth. It was reported that Rydberg sensing systems can sense microwaves of frequencies from DC up to 1THz. Its quantum nature would possibly avoid internal thermal (Johnson) noise, even at room temperature. Recent demonstrations have also observed high precision for terahertz imaging, strong fields sensing, proof-of-principle communication. However, limitations of this novel system have not been addressed, especially for a practical radar, communication or electronic warfare system. Here in this work, we first compare the architectures of different microwave receivers and then analyze the metrics of Rydberg microwave receivers, such as instantaneous bandwidth and dynamic range based on experimental results. We concluded by pointing out several main obstacles to overcome for realizing a practical state-of-the-art microwave receiver.
Due to the exaggerated properties of highly excited atomic states, a Rydberg-atom-based microwave receiver holds the promise to achieve superior performances in microwave metrology and communication when compared to conventional antennas. However, developing long-distance communication applications based on Rydberg atomic receiver remains challenging, because it requires the simultaneous achievement of low bit error rate (BER), high symbol rate, and weak carrier amplitude. The key to tackle this problem is to encode the information with a proper scheme that maintains high sensitivity and robustness of the Rydberg atomic receiver. Here, we use Rydberg atom-based heterodyne detection for the reception of phase-modulated microwave field, and demonstrate more than one order of magnitude improvement in reception sensitivity compared to the previously investigated amplitude-modulation scheme. Therefore, we achieve low BER communication with high symbol rate of 12 k bit/s and weak carrier amplitude of $13\phantom{\rule{0.2em}{0ex}}\text{\ensuremath{\mu}}\mathrm{V}\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ simultaneously. Furthermore, we also demonstrate that our scheme is compatible with frequency-division-multiplexing communication.
In recent years, electric field measurement techniques based on Rydberg atoms have shown unique advantages in high sensitivity and wideband applications and miniaturization. The Rydberg atom receiver senses the electromagnetic signal using the quantum coherence effect, which overcomes the inherent defects of traditional electronic receivers in terms of thermal noise, insertion loss of microwave devices, and the use of wavelength-dependent antennas, thus providing the Rydberg atomic receivers the potential to become the next generation of microwave receivers. For some particular application scenarios such as radar and communication, superheterodyne reception is a critical technical approach, and the linear dynamic range is an essential factor in evaluating the performance of the superheterodyne receivers. It is challenging to promote the Rydberg atomic receiver without figuring out the influence of system parameters on the linear dynamic range. This paper starts with the response mechanism of the Rydberg atomic superheterodyne receiver, and a theoretical model is established to simulate the atom-microwave responses. Then the harmonics' generation mechanism is discussed, and the atomic linear dynamic range under different probe light Rabi frequencies is studied further. Furthermore, a method to evaluate the antiblocking performance of the system is proposed. This work is expected to provide theoretical guidance for the design and performance optimization of the Rydberg atomic superheterodyne receiver.
Facing the trend of 5G/6G communications toward high spectral efficiency and low power consumption, RF receivers urgently need to overcome the triple challenges of high sensitivity, terahertz (THz) coverage, and system integration. Conventional approaches are limited by electronic thermal noise, band correlation and antenna perturbation effects. In this context, sensors based on the Rydberg atom become a promising alternative, with his large electric dipole moment bringing extremely high sensitivity, inherent frequency selectivity, and the potential to build low-power integrated photonic platforms. This paper describes a Rydberg atomic RF sensor using a quantum coherent mechanism to receive and demodulate quadrature AM signals. The core innovations include: (1) a scheme for 4QAM signal splitting and demodulation within the atomic resonance region via precise signal control; and (2) dynamic, real-time control of the demodulation channels (I/Q paths) by exploiting the phase difference between the local oscillator (LO) and signal (SIG) fields. The proposed architecture can support demodulation of quadrature AM signals, demonstrating its great potential as a versatile next-generation communications platform.
Quantum sensing has attracted significant attention due to its ability to measure physical quantities with extremely high accuracy. Rydberg atoms - typically alkali atoms with a highly excited valence electron that is far from the nucleus - exhibit strong sensitivity to external electromagnetic fields. This sensitivity leads to coupling between different atomic energy levels, which can be observed by monitoring changes in a control laser beam before and after it passes through a vapor cell containing the Rydberg atoms. By analyzing the transmitted laser signal with a photodetector, variations in transmission can be attributed to the presence and characteristics of the external electromagnetic field. Because Rydberg atoms operate in a highly excited quantum state without relying on traditional electronic circuitry, they inherently avoid thermal noise, thereby enabling more sensitive detection. In this paper, we investigate the performance of a Rydberg atomic receiver based on Rb-85 and compare it with that of a conventional receiver in detecting an 8-level pulse amplitude modulation (8-PAM) signal in the presence of off-resonant interference. We demonstrate that the Rydberg receiver can suppress interference without the need for an additional filter. Effectively, our results show that the Rydberg receiver serves as an integrated filter and demodulator, outperforming conventional circuit-based receivers in terms of achievable symbol error rate