Improving the bandwidth of Rydberg atom-based receivers is an ongoing challenge because of the long-lived Rydberg state lifetimes that limit the refresh rate of ground-state atoms. In particular, the local oscillator (LO)-based Rydberg mixer approach allows for bandwidths in a few MHz ranges. Here, we use the laser parameters of the Rydberg atomic receiver superheterodyne detection technology to study their respective bandwidths. We have confirmed through experiments that laser power and waist diameter can affect the Rabi frequency and thus alter the instantaneous bandwidth. The experimental results indicate that the instantaneous bandwidth is directly proportional to the Rabi frequency of the coupled light and inversely proportional to the Rabi frequency of the probe light. Optimal parameters for quantum sensing applications are identified through powerdependent Rabi oscillation measurements.
Improving the bandwidth of Rydberg atom-based receivers is an ongoing challenge because of the long-lived Rydberg state lifetimes that limit the refresh rate of ground-state atoms. In particular, the local oscillator (LO)-based Rydberg mixer approach allows for bandwidths in a few MHz ranges. Here, we use the laser parameters of the Rydberg atomic receiver superheterodyne detection technology to study their respective bandwidths. We have confirmed through experiments that laser power and waist diameter can affect the Rabi frequency and thus alter the instantaneous bandwidth. The experimental results indicate that the instantaneous bandwidth is directly proportional to the Rabi frequency of the coupled light and inversely proportional to the Rabi frequency of the probe light. Optimal parameters for quantum sensing applications are identified through powerdependent Rabi oscillation measurements.
Improving the bandwidth of Rydberg-atom-based receivers is an ongoing challenge owing to the long-lived Rydberg state lifetimes that limit the refresh rate of ground-state atoms. In particular, the local-oscillator-based Rydberg mixer approach allows for bandwidths into the few-megahertz range. Here we use heterodyne detection of the Rydberg-atom receiver probe laser to separate the negative and positive sidebands that originate from distinct six-wave-mixing processes, in order to investigate their individual bandwidths. We experimentally confirm the prediction that the negative sideband exhibits a higher bandwidth than the positive sideband. We further explore the effect of coupling and probe laser Rabi frequency on the bandwidth, which we find to be in close agreement with our model. We achieve maximum experimental (and theoretical) bandwidths of $10.5\ifmmode\pm\else\textpm\fi{}0.4$ (11.6) and $3.4\ifmmode\pm\else\textpm\fi{}0.2$ (5.4) MHz for the negative and positive sidebands, respectively, from the $\ensuremath{-}3$ dB roll-off point for optimized field parameters. This work provides insight into the bandwidth-limiting features of Rydberg-atom receivers and points the way towards further optimization of their response.
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.
In the field of Instrumentation & Measurement (I&M), overcoming the inherent trade-off between instantaneous bandwidth and sensitivity in Rydberg atom-based microwave electrometry remains a significant challenge. We propose a novel method of co-optimizing the Rabi frequencies of dual microwave fields (LO and SIG). This enables simultaneous enhancement of instantaneous bandwidth and sensitivity in a Rydberg-based receiver. In experimental settings, the significant power disparity between heterodyne fields typically necessitates an increase in the power of the local oscillator (LO) field. Conventional measurement techniques under such high power differentials can induce high-order harmonics—a phenomenon associated with the Floquet effect—resulting in deviations from resonant behavior and an increase in noise. This, in turn, reduces the atomic population distribution and constrains the system bandwidth. Leveraging the sensitivity enhancement mechanisms provided by electromagnetically induced transparency (EIT) and Autler–Townes (AT) splitting, we experimentally characterized the relationship between the Rabi frequencies of the LO and the target signal (SIG) microwave fields. Our approach enables the optimization and fine-tuning of parameters of the auxiliary microwave field to mitigate performance degradation caused by these nonlinear effects, thereby extending the frequency response of the system beyond the limitations of conventional resonance-based methods. As a result, our team has achieved an instantaneous bandwidth of 7.1 MHz coupled with a sensitivity of 51nV cm−1Hz−1/2under a -41 dBm power difference condition. This work establishes a new instrumentation framework for high-dynamic-range sensing, directly addressing I&M limitations in nonlinear artifact suppression.
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.
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.
We optimize theoretically and experimentally the performances of the recently demonstrated modulation transfer protocol [D.-A. Trinh, K. V. Adwaith, M. Branco, A. Rouxel, S. Welinski, P. Berger, F. Goldfarb, and F. Bretenaker, Applied Physics Letters 125, 154001 (2024)] aiming at extending the bandwidth of quantum RF receivers based on hot Rydberg atoms. This optimization relies on tuning the parameters of the phase modulation of the coupling beam, which is converted by the nonlinear response of the atoms into an amplitude modulation of the probe beam. We develop a theoretical model to optimize both the modulation frequency and the modulation amplitude of the coupling beam, thereby maximizing the atomic response. Once optimized, the sensitivity to detuned RF fields of this modulation transfer protocol is measured and compared with that of the conventional protocol. This comparison shows that the new protocol permits a strong increase in the detection bandwidth. Indeed, it outperforms the usual one as soon as the RF signal to be measured is detuned by more than a few MHz. We illustrate the capability of this modulation transfer protocol to enhance the detection bandwidth by showing experimentally how it permits to bridge the gap between two Rydberg transitions separated by 166 MHz. In all cases, the experimental results are in good agreement with the simulations.