The quantum microwave measurement technique based on Rydberg atoms enables the measurement of microwave electric field over an ultrawide frequency range. To improve the sensitivity while maintaining its broadband characteristics, we propose a tunable local electric field enhancement resonator loaded with varactor diodes. Simulation results show that the tunable frequency covers from 305 MHz to 455 MHz and the electric field enhancement multiplier is higher than 40 dB. Experimental test results based on the AC Stark effect demonstrate that the resonator has the electric field enhancement capability from 323 MHz to 443 MHz by changing the bias voltage of the varactor diode. This tunable electric field enhancement resonator is expected to improve the ability of quantum microwave technology in broadband measurements.
The quantum microwave measurement technique based on Rydberg atoms enables the measurement of microwave electric field over an ultrawide frequency range. To improve the sensitivity while maintaining its broadband characteristics, we propose a tunable local electric field enhancement resonator loaded with varactor diodes. Simulation results show that the tunable frequency covers from 305 MHz to 455 MHz and the electric field enhancement multiplier is higher than 40 dB. Experimental test results based on the AC Stark effect demonstrate that the resonator has the electric field enhancement capability from 323 MHz to 443 MHz by changing the bias voltage of the varactor diode. This tunable electric field enhancement resonator is expected to improve the ability of quantum microwave technology in broadband measurements.
Quantum microwave measurement techniques based on Rydberg atoms have the advantages of self-calibration, low interference with external electric fields, and a wide range of measurement frequencies. However, the current quantum microwave sensitivity measurement capability is not yet comparable to that of classical receivers. Loading the electric field enhancement structure outside the vapor cell can effectively improve its sensitivity, but at the same time, it also leads to the narrowing of the measurement bandwidth. To fully utilize the advantages of quantum microwave measurement technology, we propose a tunable local electric field enhancement structure by combining a varactor diode, its tuning frequency covers 0.286 to 0.427 GHz, and the electric field enhancement ranges from 120 to 712.
Quantum microwave measurement based on Rydberg atoms is a novel microwave measurement technique. To improve its measurement sensitivity over a broadband, this letter presents a mechanically tunable electric field enhancement device, loaded on the the vapor cell. By adjusting the length of the split ring resonator, an electric field enhancement capability of more than 30 dB over a bandwidth of 0.52 GHz to 1.54 GHz is realized in simulation. The experimental results show that its resonance frequency covers from 0.52 GHz to 1.86 GHz with a relative bandwidth of 113%, exhibiting excellent broadband performance. This broadband electric field enhancement device is expected to further improve the performance of quantum microwave measurements.
The quantum microwave measurement technique based on Rydberg atoms has the significant advantages of traceability and self-calibration. To improve the measurement sensitivity of this technique, the electric field local enhancement structure based on microwave resonators has been proposed. However, most electric field local enhancement structures work only at a single frequency. In this paper, a dual-frequency electric field local enhancement structure based on double split-ring resonators (DSRR) is proposed. The simulation results show that the structure achieves 27 dB and 33 dB enhancement of electric field strength at 1.17 GHz and 1.74 GHz with local enhancement and uniform enhancement of the electric field at the cell, respectively. For experimental tests, it is verified that the structure has an electric field local enhancement effect at dual frequencies by the AC Stark effect and the superheterodyne signal reception method based on Rydberg atoms, effectively improving the sensitivity of quantum microwave measurements.
In this article, we propose a tunable multilayered resonator (TMR) to achieve broadband high-sensitivity sensing within a deep-subwavelength structure. The proposed TMR significantly enhances the incident electric field for Rydberg atoms, improving the sensitivity of the room-temperature atomic sensor. Additionally, by incorporating varactor diodes, the resonant frequency of the TMR can be dynamically controlled by adjusting the diode bias voltage. In the experiment, the TMR realized a 45.26% relative bandwidth, ranging from 13.19 MHz to 19.16 MHz. Furthermore, the sensitivity of the system reached 0.13 µV/cm/Hz in the presence of the TMR at 19.16 MHz, compared to only 24.59 µV/cm/Hz without the TMR.
Rydberg atom-based microwave measurement technology has gained attention for its self-calibration, high sensitivity, and wide frequency response. To enhance sensitivity, resonators are typically employed for localized electric field enhancement. With the introduction of AC/DC Stark tuning and laser scanning techniques, resonator designs have been developed to support extended frequency coverage. However, these require sequential scanning or switching to cover the target range, limiting their applicability in passband-wide, multi-frequency detection. To address this issue, this paper proposes a cascaded cavity resonator (CCR) that enables continuous field enhancement within the target S-band range. A theoretical model was established and the key dimensions were optimized via COMSOL-based simulation of the vapor cell's spatial field distribution. Subsequently, validation through Autler-Townes (AT) effect and heterodyne technology confirms that the proposed structure enhances sensitivity by$ \geq$27.2 dB within the 2.781-3.008 GHz bandwidth. This work supports systematic exploration of Rydberg-atom response across a broader spectral range and enables multi-frequency detection without stepwise tuning.
We demonstrate a method for broadband tunable continuous frequency electric field measurement based on the DC Stark effect in Rydberg atoms. In our experiment, we place a pair of parallel electrode plates inside the atomic vapor cell, utilizing the DC Stark effect to induce splitting and shifting of the Rydberg energy levels, thereby altering the resonance frequency of the Stark subpeaks. By employing the 52D5/2 Rydberg state, we achieve electric field measurements in the frequency range of 5.083–14.470 GHz. At an EDC of 3.45 V/cm and a resonant microwave frequency of 14.470 GHz, using heterodyne technology, the microwave electric field sensitivity is 538.89 μV/cm/√Hz, with a linear dynamic range of 23 dB. In comparison, a Rydberg heterodyne receiver with an EDC of 0 V/cm and a resonant microwave frequency of 5.083 GHz has a sensitivity of 5.43 μV/cm/√Hz and a linear dynamic range of 51 dB. This work will promote the study of atomic microwave receivers in continuous microwave frequency measurement.