We present a theoretical and experimental investigation of the improvement and determination of the sensitivity of Rydberg atom-based microwave RF sensor. An optical Bloch equation has been set up based on the configuration that two-color cascading lasers exciting atom to highly Rydberg state and a microwave RF coupling this Rydberg state to its adjacent neighbor. The numerical simulation shows that the sensitivity of the atomic RF sensor is correlated with the amplitude strengths of the applied two lasers and the RF itself. It also depends on the frequency detuning of the coupling laser, which induces an asymmetrically optical splitting. The coupling laser frequency fixing at the shoulder of the stronger one is more favorable for a higher sensitivity. Accordingly, we perform an experimental demonstration for the optimization of all these parameters and the sensitivity is improved to 12.50(04) ${\mathrm{nVcm}}^{-1}$·Hz${}^{-1/2}$.

The Rydberg atom-based microwave electric field sensor has high sensitivity for weak RF-field detection. Selection of Rydberg states with larger electric dipole moment is beneficial to enhance the sensitivity, and we choose Rydberg states with its principal quantum number up to n ∼ 80. We study the probe laser transmission response to a microwave field for these chosen high Rydberg states at room temperature. It agrees well with theoretical simulation based on an optical Bloch equation with considered microwave-atom interaction and Doppler broadening effect. In our experiment, the microwave sensing sensitivity based on 85 Rb transition | 78 S 1 / 2 ⟩ → | 78 P 3 / 2 ⟩ arrives at 5.102(49) nV cm − 1 Hz − 1 / 2 at 1 kHz.

A microwave electric field sensing has been set up based on a three-color electromagnetically induced absorption in rubidium vapor cell via cascading transitions. All transitions are irradiated by infrared lasers: a 780 nm laser servers as probe to monitor the optical transmittancy via transition 5S_1/2→P_3/2;, a 776 nm laser and a 1260 nm laser are used to couple the states 5P_3/2 and 5D_5/2 and states 5D_5/2 and 44F_7/2, respectively. We find that a frequency detuning ∼2π × ( − 40) MHz of the 776 nm dressing beam prefers to a better signal-to-noise ratio for the probe beam. The off-resonance greatly depresses the double resonance pumping effect. A demonstration measurement for the electric field of microwave 1.18988 GHz, corresponding to the coupling resonance between two adjacent Rydberg states 44F_7/2 and 44F_9/2, gives a sensitivity of 55.79 ( 23 ) nVcm − 1 / Hz and a smallest discernible electric field of 78.9(33) nVcm⁻¹ in time scale of 500 ms.

We have demonstrated a Rydberg atom-based two-band communication with the optically excited Rydberg state coupled to another pair of Rydberg states by two microwave fields, respectively. The initial Rydberg state is excited by a three-color electromagnetically-induced absorption in rubidium vapor cell via cascading transitions, with all of them located in infrared bands: a 780 nm laser servers as a probe to monitor the optical transmittancy via transition $5{\mathrm{S}}_{1/2}\to 5{\mathrm{P}}_{3/2}$, 776 nm and 1260 nm lasers are used to couple the states $5{\mathrm{P}}_{3/2}$ and $5{\mathrm{D}}_{5/2}$ and states $5{\mathrm{D}}_{5/2}$ and $44{\mathrm{F}}_{7/2}$. Experimentally, we show that two channel communications carried on the two microwave transitions influence each other irreconcilably, so that they cannot work at their most sensitive microwave-optical conversion points simultaneously. For a remarkable communication quality for both channels, the two microwave fields both have to make concessions to reach a common microwave-optical gain. The optimized balance for the two microwave intensities locates at $E_{\mathrm{MW}1}=6.5 \mathrm{mV}/\mathrm{cm}$ and $E_{\mathrm{MW}2}=5.5 \mathrm{mV}/\mathrm{cm}$ in our case. This mutual exclusive influence is theoretically well-explained by an optical Bloch equation considering all optical and microwave field interactions with atoms.

Electric field measurement techniques based on Rydberg atoms have proven to have unique advantages in high sensitivity and have drawn wide attention in microwave electric field metrology and communication. The Rydberg states employed for microwave sensing are usually excited by two- or three-step laser irradiation. It leads to the Rydberg atoms being populated by some specific magnetic quantum number states determined by the laser polarization configurations, whose further coupling to another Rydberg state is also constrained by the microwave polarization. Based on a three-laser optical excitation, we demonstrate this effect on the microwave spectra of the 85Rb transitions 41F7/2 → 42D5/2 and 41F7/2 → 41G7/2 at various combining polarization configurations. It shows a strong polarization dependence on the microwave spectrum and then affects the sensitivity of Rydberg atom-based microwave field sensing. Advisable polarization schemes for higher sensitivity are suggested by the two types of transitions.

Accurate measurement of high voltages is required to guarantee the safe and stable operation of power systems. Modern power systems, which are mainly based on new energy sources, require high-voltage measurement instruments and equipment with characteristics such as high accuracy, wide frequency bandwidth, broad operating ranges, and ease of operation and maintenance. However, it is difficult for traditional electromagnetic measurement transformers to meet these requirements. To address the limitations of conventional Rydberg atomic measurement methods in low-frequency applications, this paper proposes an enhanced Rydberg measurement approach featuring high sensitivity and strong traceability, thereby enabling the application of Rydberg-based measurement methodologies under power frequency conditions. In this paper, a 110 kV high-voltage measurement method based on Rydberg atoms is studied. A power-frequency electric field measurement device is designed using Rydberg atoms, and its internal electric field distribution is analyzed. Additionally, a decoupling method is proposed to facilitate voltage measurements under multi-phase overhead lines in field conditions. The feasibility of the proposed method is confirmed, providing support for the future development of practical measurement devices.