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
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
The highly-excited Rydberg states are with a unique property of radio-frequency (RF) resonance, and Rydberg atoms at room temperature are promising for developing a broadband RF electric field sensor and relevant metrology standards. In this paper, the working mechanism of an atomic amplitude-modulation(AM) radio receiver is investigated in detail, and various factors affecting the communication quality are discussed. The modulation RF signal can be directly retrieved by measuring the transmission of a probe laser at resonance of rubidium D2 transition using a fast photo-diode detector, without any conventional demodulation process. Various communication experiments are tested at a 10.22 GHz carrier, and a modulation bandwidth of 1 MHz and an acceptable data transfer rate of about 1 Mbps have been achieved using current detection techniques. Owing to a potential high sensitivity and ultra-broadband capability of free-space RF field sensing, the quantum receiver has great significance compared with conventional electronics-based receivers, including but not limited to a weak signal, long-distance, and broadband communication in free space or via a fiber link.
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.
With the escalating development of the quantum information technologies, the Rydberg atomic receiver has been envisioned as a promising alternative to its classical electronic counterparts, attracting extensive attentions from both physics and electronic engineering disciplines. By exploiting the electrical acuteness of Alkali atoms with diverse Rydberg energy states for electromagnetic field measurement, Rydberg atomic receiver is capable of surmounting the inherent limitations on the operating bandwidth and detection sensitivity of the classical electronic counterparts. Against this background, this article provides an extensive overview of Rydberg atomic communication and sensing from fundamental theory, critical technologies to practical implementations. Firstly, the milestones of the Rydberg atomic receiver evolution was introduced. Then we provide a clear understanding of Rydberg atomic receiver mechanisms from the perspective of classical communication and sensing, and highlight the unprecedented advantages over traditional electronic receivers as well as the technical challenges. Afterwards, necessary fundamentals are presented including the Rydberg atoms, typical non-coherent/coherent structures, and explicit experimental configurations, followed by discussions on state-of-the-art development of the Rydberg atomic receiver. Specifically, advancements on electric-field detection methods for accurate measurement of amplitude, phase, frequency and polarization, are extensively investigated. Based on the established methodologies, recent innovations in Rydberg atomic communication and sensing are reviewed, ranging from waveform design and array-based signal processing to radar applications like localization, imaging and remote sensing, with practical experimental results presented. Finally, we summarize the promising research trends around Rydberg atomic receiver.
As a key enabler for next-generation wireless systems, integrated sensing and communication (ISAC) requires significantly higher receiver sensitivity than conventional architectures to achieve long-range target detection, thereby introducing new challenges in receiver design. Among potential solutions, Rydberg atomic quantum receivers (RAQRs) have attracted growing attention for their unique quantum sensing capabilities. By exploiting the exceptional responsiveness of Rydberg atoms to electromagnetic fields, RAQRs enable direct and highly sensitive measurement of radio-frequency (RF) signals without relying on traditional antenna-based front ends. However, this enhanced sensitivity also renders them more vulnerable to interference, particularly from undesired targets and long-delay multipath components. To address this limitation, this article presents practical strategies for improving the interference robustness and selective reception performance of RAQRs in ISAC scenarios. Specifically, we begin with a comprehensive overview of RAQR principles and identify the interference-related challenges encountered in ISAC applications. Building on this foundation, we introduce the Actively Selective RAQR (AS-RAQR) architecture, which integrates tunable gating mechanisms to actively suppress unwanted signals. The proposed design is validated through representative case studies, followed by a discussion of open challenges and future research directions.
Abstract Rydberg atom-based sensors use atoms dressed by lasers to detect and measure radio frequency electromagnetic fields. The absorptive properties of the atomic gas, configured as a Rydberg atom-based sensor, change in the presence of a radio frequency electromagnetic field. While these sensors are reasonably sensitive, the best conventional radio frequency sensors still outperform Rydberg atom-based sensors with respect to sensitivity. One approach to increase the sensitivity of Rydberg atom-based sensors is to engineer the vapor cell that contains the atomic gas. In this work, we introduce a passive, all-dielectric amplifier integrated into a Rydberg atom-based sensor vapor cell. The vapor cell is a combination of a slot waveguide and a photonic crystal. The structural features of the vapor cell yield a power amplification of ~ 24 dB. The radio frequency electromagnetic field is coupled adiabatically into the slot waveguide and slowed to increase the interaction between the radio frequency field and the atoms to effectively amplify the incoming signal, i.e., increase the Rabi frequency on the radio frequency transition. The work shows the utility of vapor cell engineering for atom-based quantum technologies and paves the way for other such devices.
Rydberg atoms have been extensively utilized in microwave measurement with high sensitivity, which has great potential in the field of communication. In this study, we discuss the digital communication based on a Rydberg atomic receiver under simultaneously coupling by resonant and near detuning microwaves. In addition, we verify the feasibility of the Rydberg atom-based frequency division multiplexing (FDM) in microwave communication. We demonstrate the principle and performance of the atom-based FDM receiver by applying amplitude modulation (AM) and frequency modulation (FM), respectively. To demonstrate the actual communication performance at different data transfer rates, we consider monochromatic images as an example. The experimental results show that the maximum acceptable data transfer rate of both AM and FM is about 200 kbps, whereas their maximum bit error rates (BER) is less than 5%. When compared with the traditional electronic receiver, this atomic receiver, which is compatible with FDM, has numerous advantages, such as small size, low power consumption, and high sensitivity. Furthermore, this receiver has a strong ability of anti-electromagnetic interference, and the signals transmitted do not interfere with each other in different channels.