Rydberg atoms possess a large electric dipole moment and exhibit high sensitivity to electromagnetic signals. Receivers based on Rydberg atoms represent a novel reception mechanism, demonstrating broad application prospects in the field of communication. Current research has not addressed the influence of the operating parameters of Rydberg atomic receiver on channel capacity. This study establishes a channel capacity model for Rydberg atomic receiver based on Shannon's formula and the response mechanism of the electromagnetically induced transparency (EIT) effect. Using this model, the influences of atomic number density, laser beam waist, and coupling laser Rabi frequency on the channel capacity of Rydberg atomic receiver are analyzed. A strategy for optimizing channel capacity by adjusting the coupling laser Rabi frequency is proposed, and an analytical solution for the Rabi frequency that maximizes channel capacity is derived. The accuracy of this analytical solution is then verified through numerical simulations. The channel capacity corresponding to the analytical solution in this study is similar to the optimal channel capacity obtained using the one-dimensional optimization method (Newton’s method) and is superior to the results obtained by the quadratic interpolation method, demonstrating the effectiveness of the proposed analytical solution in optimizing the channel capacity of Rydberg atomic receiver. This research provides theoretical guidance for designing high-performance Rydberg atomic receiver and optimizing channel capacity.
Rydberg atoms possess a large electric dipole moment and exhibit high sensitivity to electromagnetic signals. Receivers based on Rydberg atoms represent a novel reception mechanism, demonstrating broad application prospects in the field of communication. Current research has not addressed the influence of the operating parameters of Rydberg atomic receiver on channel capacity. This study establishes a channel capacity model for Rydberg atomic receiver based on Shannon's formula and the response mechanism of the electromagnetically induced transparency (EIT) effect. Using this model, the influences of atomic number density, laser beam waist, and coupling laser Rabi frequency on the channel capacity of Rydberg atomic receiver are analyzed. A strategy for optimizing channel capacity by adjusting the coupling laser Rabi frequency is proposed, and an analytical solution for the Rabi frequency that maximizes channel capacity is derived. The accuracy of this analytical solution is then verified through numerical simulations. The channel capacity corresponding to the analytical solution in this study is similar to the optimal channel capacity obtained using the one-dimensional optimization method (Newton’s method) and is superior to the results obtained by the quadratic interpolation method, demonstrating the effectiveness of the proposed analytical solution in optimizing the channel capacity of Rydberg atomic receiver. This research provides theoretical guidance for designing high-performance Rydberg atomic receiver and optimizing channel capacity.
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.
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.
Measurement sensitivity is crucial for the practical application of Rydberg atomic microwave superheterodyne receiver systems in communication, radar, and navigation. Based on laser-atom-microwave interaction mechanisms, the influence of laser powers and local-oscillator (LO) microwave field intensity on measurement sensitivity is systematically studied in this paper. Measurement sensitivity is analyzed through electromagnetically induced transparency (EIT) spectral characteristics, specifically EIT amplitude and full-width-half-maximum (FWHM),larger amplitudes and narrower FWHM indicate improved signal-to-noise ratios. For a 60D-state Rydberg atomic system with fixed probe and coupling laser beam waists (800 µm and 875 µm), optimal parameters are determined: probe laser power of 60 µW(Rabi frequency: 2π×7.02 MHz), coupling laser power of 40 mW (Rabi frequency: 2π×0.66 MHz), and LO microwave Rabi frequency of 2π×8.34 MHz. Experimental results demonstrate a 4.6 dB sensitivity enhancement, advancing from −137.5dBm/Hz to −142.1 dBm/Hz at 3.21 GHz microwave field. This improvement is attributed to precise alignment of laser-atom and microwave-atom interactions, bridging the gap toward quantum sensitivity limits.
Abstract We investigate the response bandwidth of a superheterodyne Rydberg receiver at a room-temperature vapor cell, and present an architecture of atomic array to increase the response bandwidth. Two microwave fields, denoted as a local oscillator (LO) ELO and a signal field ESig, couple two Rydberg states transition of |52D5/2⟩ → |53P3/2⟩. In the presence of the LO field, the frequency difference between two fields can be read out as an intermediate frequency (IF) signal using Rydberg electromagnetically induced transparency (EIT) spectroscopy. The bandwidth of the Rydberg receiver is obtained by measuring the output power of IF signal versus the frequency difference between two fields. The bandwidth dependence on the Rabi frequency of excitation lasers is presented, which shows the bandwidth decrease with the Rabi frequency of probe laser, while it is quadratic dependence on the Rabi frequency of coupling laser. Meanwhile, we investigate the effect of probe laser waist on the bandwidth, showing that the bandwidth is inversely proportional to the laser waist. We achieve a maximum response bandwidth of the receiver about 6.8~MHz. Finally, we design an architecture of atomic array for increasing the response and keeping the sensitivity, simultaneously. Our work has the potential to extend the applications of Rydberg atoms in communications.
Rydberg atom can respond to weak microwave electric field signal in real-time by using its electromagnetically induced transparency effect to realize down conversion of space microwave electric field signal, which can be used as a superheterodyne receiver. The Rydberg atom superheterodyne receiver is a new receiving system composed of Rydberg atoms, photodetectors, and electronic information processing modules. Presently, the physical response mechanism of Rydberg atomic superheterodyne receiving technology is studied in depth. However, no complete receiving link analysis model has been established, which is not conducive to optimizing its system performance. Based on the physical mechanism of the Rydberg atom responding to the microwave electric field, this paper introduces the concept of intrinsic expansion coefficient, establishes and experimentally verifies the receiving link model of the Rydberg atom superheterodyne receiver, and briefly discusses the influence of the intrinsic expansion coefficient on the system sensitivity and response characteristics, thereby providing the theoretical guidance for optimizing the performance of the Rydberg atom superheterodyne receiving system. In the end, the Rydberg atomic and the electronic receiving links' sensitivity performance is discussed and compared.
This paper investigates the dynamic solution of the density matrix equation based on the Rydberg atom superheterodyne structure. Compared to the current analytical method relying on the steady-state solution, the dynamic solution is related to the Rabi frequency and the frequency of the signal to be measured. Therefore, it can comprehensively describe the instantaneous bandwidth and gain characteristics of the receiver and is in good agreement with experimental results. Additionally, we propose an atomic all-heterodyne receiver architecture that combines electric-field heterodyne and optical heterodyne techniques and demonstrates the reception and recovery of modulated signals under this architecture with linear frequency modulation (LFM) signals as an example. Our research offers interesting theoretical insights that can be applied to the performance analysis and system optimization of atomic receivers.