With the advancement of quantum physics and deeper exploration of atomic systems, the integration of atoms into communication systems has garnered significant attention. Among these efforts, the use of Rydberg atoms as a communication receiver has emerged as a prominent area of research. In this work, we introduce a new mathematical modeling approach to more accurately establish the input-output relationship of a Rydberg atomic receiver. We categorize this relationship into three segments: one linear region and two nonlinear regions, facilitating a comprehensive analysis of the nonlinear challenges associated with Rydberg atomic receiver. Our findings indicate that adjusting the Rabi oscillation frequency of the coupling laser can effectively extend the linear operating range of the receiver. Furthermore, focusing on complex quadrature amplitude modulation, we propose a digital nonlinear distortion compensation method specifically designed for Rydberg atomic receiver. This method demonstrates a significant improvement in performance, enhancing the demodulation bit error rate compared to conventional linearization techniques.
With the advancement of quantum physics and deeper exploration of atomic systems, the integration of atoms into communication systems has garnered significant attention. Among these efforts, the use of Rydberg atoms as a communication receiver has emerged as a prominent area of research. In this work, we introduce a new mathematical modeling approach to more accurately establish the input-output relationship of a Rydberg atomic receiver. We categorize this relationship into three segments: one linear region and two nonlinear regions, facilitating a comprehensive analysis of the nonlinear challenges associated with Rydberg atomic receiver. Our findings indicate that adjusting the Rabi oscillation frequency of the coupling laser can effectively extend the linear operating range of the receiver. Furthermore, focusing on complex quadrature amplitude modulation, we propose a digital nonlinear distortion compensation method specifically designed for Rydberg atomic receiver. This method demonstrates a significant improvement in performance, enhancing the demodulation bit error rate compared to conventional linearization techniques.
Abstract The Rydberg atom-based receiver, as a novel type of antenna, demonstrates broad application prospects in the field of microwave communications. However, since Rydberg atomic receivers are nonlinear systems, mismatches between the parameters of the received amplitude modulation (AM) signals and the system’s linear workspace and demodulation operating points can cause severe distortion in the demodulated signals. To address this, the article proposes a method for determining the operational parameters based on the mean square error (MSE) and total harmonic distortion (THD) assessments and presents strategies for optimizing the system’s operational parameters focusing on linear response characteristics (LRC) and linear dynamic range (LDR). Specifically, we employ a method that minimizes the MSE to define the system’s linear workspace, thereby ensuring the system has a good LRC while maximizing the LDR. To ensure that the signal always operates within the linear workspace, an appropriate carrier amplitude is set as the demodulation operating point. By calculating the THD at different operating points, the LRC performance within different regions of the linear workspace is evaluated, and corresponding optimization strategies based on the range of signal strengths are proposed. Moreover, to more accurately restore the baseband signal, we establish a mapping relationship between the carrier Rabi frequency and the transmitted power of the probe light, and optimize the slope of the linear demodulation function to reduce the MSE to less than 0.8 × 10 −4 . Finally, based on these methods for determining the operational parameters, we explore the effects of different laser Rabi frequencies on the system performance, and provide optimization recommendations. This research provides robust support for the design of high-performance Rydberg atom-based AM receivers.
The intrinsic integration of Rydberg atomic receivers into wireless communication systems is proposed, by harnessing the principles of quantum physics in wireless communications. More particularly, we conceive a pair of Rydberg atomic receivers, one incorporates a local oscillator (LO), referred to as an LO-dressed receiver, while the other operates without an LO and is termed an LO-free receiver. The appropriate wireless model is developed for each configuration, elaborating on the receiver's responses to the radio frequency (RF) signal, on the potential noise sources, and on the signal-to-noise ratio (SNR) performance. The developed wireless model conforms to the classical RF framework, facilitating compatibility with established signal processing methodologies. Next, we investigate the associated distortion effects that might occur, specifically identifying the conditions under which distortion arises and demonstrating the boundaries of linear dynamic ranges. This provides critical insights into its practical implementations in wireless systems. Finally, extensive simulation results are provided for characterizing the performance of wireless systems, harnessing this pair of Rydberg atomic receivers. Our results demonstrate that LO-dressed systems achieve a significant SNR gain of approximately 40~50 dB over conventional RF receivers in the standard quantum limit regime. This SNR head-room translates into reduced symbol error rates, enabling efficient and reliable transmission with higher-order constellations.
Image interference is a common issue in heterodyne reception structures, introducing co-channel interference and degrading performance. Although the heterodyne structure significantly improves the sensitivity of the Rydberg-atom-based receiver, the presence of image interference limits its practical application. In this work, we design a quadrature reception structure with a Rydberg-atom-based receiver and experimentally evaluate its performance. This architecture provides orthogonal receiving channels, down-converting input signals into complex form and enabling the separation of image-frequency components. Experiments confirm that conventional heterodyne reception suffers from image interference, while our quadrature structure effectively cancels it after channel compensation. The demonstrated Rydberg-atom-based quadrature receiver shows strong potential for wireless communication and precision measurement, especially in multi-signal environments.
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.
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.
We demonstrate an atom-based amplitude-modulation (AM) receiver for digital communication with a weak continuous frequency carrier using a Rydberg AC Stark effect in a vapor cell and achieve the operating carrier frequency continuously from 0.1 GHz to 5 GHz at a single Rydberg state. A strong local oscillator (LO) field E LO acts as a gain to shift the Rydberg level to a high sensitivity region, and a weak carrier field E Carr keeps the same frequency with the LO field. The digital baseband signals are encoded onto the E Carr using the amplitude modulation technique with the different modulation frequency. The response of Rydberg atom to the baseband signal is probed via a Rydberg electromagnetically induced transparency (EIT). The measured instantaneous bandwidth of the system is about 230 kHz. To demonstrate the performance of our system for an actual communication, we consider a color image as an example, the received image displays that the bit error rate (BER) is less than 5% when the maximum data transfer rate is about 238 kbps. Meanwhile, our system shows the weak carrier field of E Carr ≥ 13.52 μ V/cm can be used for the practical communication with BER less than 5%. Our works break the limitation that EIT-AT based atomic receivers only operate at the near resonant frequencies of the Rydberg transitions, making this emerging of quantum technology close to the practical application with high sensitivity and broad bandwidth.