Quantum measurement based on Rydberg atoms enables self-calibrated, high-precision, and high-dynamic-range electric field sensing, meeting the stringent demands of modern power systems. However, low-frequency AC voltage measurement using Rydberg atoms is still in its early stage, with key techniques yet to mature. This paper proposes a dual-photon, three-level excitation scheme with both probe and coupling lasers frequencylocked to atomic transitions. Then the light intensity of transmitted probe varies periodically with the applied AC field, allowing extraction of amplitude, frequency, and phase for electric field reconstruction. The mathematical models of light intensity after dual-laser locking and applied electric field are established in this paper. To suppress the influence of signal distortion and noise on measurement accuracy, an improved least mean square (LMS) adaptive algorithm is developed, dynamically adjusting the step size to mitigate non-stationary noise. Integrating the conversion relationships and processing technologies into the voltage measurement system based on Rydberg atoms, the experimental measurement for$35/\sqrt{} 3 \text{kV}$power-frequency voltage shows the measurement accuracy can reach class 0.2.
Quantum measurement based on Rydberg atoms enables self-calibrated, high-precision, and high-dynamic-range electric field sensing, meeting the stringent demands of modern power systems. However, low-frequency AC voltage measurement using Rydberg atoms is still in its early stage, with key techniques yet to mature. This paper proposes a dual-photon, three-level excitation scheme with both probe and coupling lasers frequencylocked to atomic transitions. Then the light intensity of transmitted probe varies periodically with the applied AC field, allowing extraction of amplitude, frequency, and phase for electric field reconstruction. The mathematical models of light intensity after dual-laser locking and applied electric field are established in this paper. To suppress the influence of signal distortion and noise on measurement accuracy, an improved least mean square (LMS) adaptive algorithm is developed, dynamically adjusting the step size to mitigate non-stationary noise. Integrating the conversion relationships and processing technologies into the voltage measurement system based on Rydberg atoms, the experimental measurement for35/3kVpower-frequency voltage shows the measurement accuracy can reach class 0.2.
The quantum measurement of the microwave electric field based on Rydberg atoms developed in recent years has shown promise for enhancing accuracy, sensitivity and stability. However, the study of ultra-low frequency electric field measurements in power systems is still in its early stages, presenting new challenges for Rydberg-based measurement techniques. In this work, a ladder-type two-photon three-level structure of Cs atoms is selected, and the corresponding experimental system is constructed. Two kinds of laser control schemes, which are referred to as mismatch and match measurement schemes, are then proposed, and the quantum effect’s optical spectrum is obtained by using the two measurement schemes. After these measured spectral properties are compared, the match measurement scheme is chosen for real-time measurement of ultra-low frequency electric fields. Additionally, dynamic models of the interactions among the laser field, ultra-low frequency electric field and atoms are derived, on the basis of which theoretical simulations are being conducted to study the effects of the input parameters of the electric field and laser power on the optical spectrum. On the basis of the optical spectral features, an inversion method for the excitation electric field in real time is proposed, and its effectiveness is demonstrated.
Abstract Rydberg atoms will produce the Stark effect under the action of non-resonant electric fields. Due to Rydberg atoms’ inherent energy level characteristics, they show sensitivity to electric fields and excellent self-calibration, which makes them promising in electric field measurement. In this paper, an experimental platform is established by fixing the probe and coupling laser frequencies. The ‘amplitude attenuation’ phenomenon of resonance point laser intensity oscillation caused by the change of electric field frequency is observed and analyzed, and its evolution trend is clarified; then, in different frequency bands (Hz band and kHz band), the density matrix equations are constructed and solved respectively in combination with the atomic energy level excitation structure, through which the dynamic response characteristics between atoms and AC electric fields are revealed. Finally, this paper proposes the Hz band electric field measurement method and the kHz band electric field measurement method: (1) in the steady-state solution of the electromagnetically induced transparency (EIT)-Stark mathematical model, the laser intensity curve at the resonance point laser intensity is inverted into an electric field waveform in real time to achieve Hz electric field measurement based on Rydberg atoms; (2) in the non-steady-state solution of the EIT-Stark mathematical model, the electric field amplitude is predicted by identifying the laser intensity amplitude and frequency at the laser intensity curve with the help of a neural network, thus achieving kHz electric field measurement based on Rydberg atoms. Experimental results show that the accuracy of the Hz band electric field measurement method proposed in this paper is greater than 99%, and the accuracy of the kHz band electric field measurement method is greater than 96%.
Quantum electric field measurement based on the Stark effect of Rydberg atoms has the advantages of high precision, traceability, and self-calibration. However, the current perturbation-based modeling method for the relationship between field strength and energy level shift only applies to weak fields. In applications such as power systems, electric fields can reach the kV/m level. Under such electric fields, the Rydberg state cannot ignore the strong coupling effect between adjacent highlstates, and the relationship model established by perturbation approximation is no longer accurate. This paper introduces the Landau–Zener (L-Z) tunneling model to address this limitation and describes the coupling between energy levels. It is used to construct the Rydberg atomic Hamiltonian, which includes highlstate coupling. We calculate the eigenenergies of Rydberg atoms at various electric-field strengths via matrix diagonalization, thereby obtaining a discrete mapping between field strength and energy-level shift in the strong-field regime. Subsequently, the hybrid Levenberg–Marquardt (LM) and Bayesian polynomial regression (BPR) neural network (LM-BPR) was constructed to train the discrete mapping into a continuous prediction model. In addition, the dynamic programming (DP) algorithm performs global ridge tracking on the electromagnetically induced transparency (EIT) spectrum and extracts frequency shift information from the complex EIT spectrum. Combining the above methods, strong electric field inversion based on Rydberg atoms was achieved. Experiments using the 28D5/2 Rydberg state demonstrate electric-field measurements up to 7 kV/m, with a relative error of 2.9%.
Recently, Rydberg atom has emerged as an attractive choice to realize quantum sensing of low-frequency electric field. The progress so far has mostly utilized the intensity and phase changes in probe laser and the corresponding detection mechanism still remains classical. Nevertheless, external field acting on the Rydberg state can induce the polarization variation of probe laser in the Rydberg electromagnetically induced transparency (EIT) system embedded in realistic multi-state atoms. We experimentally observe this phenomenon and realize signal extraction by appropriately utilizing the polarization degrees of freedom. Based on such a mechanism, we further design and implement a quantum weak measurement scheme, which clearly suppresses the technical noise and leads to considerable improvement of performance. Evaluation of the sensitivities across different post-selection angles demonstrates that the weak measurement results agree well with the theoretical model predictions. The advantages of our method are analyzed from multiple aspects, including characterizing the responses over different frequencies and comparing the responses of the weak measurement scheme and the traditional transmission-based method. After accounting for the screening effect of a measured ratio 17\% where the 87Rb atoms experience a substantially reduced field inside the glass cell, the performance reaches 33 μVcm-1Hz-1/2 in sensitivity and 1.0 μV/cm in minimal detectable field for an integration time of 1000 s, as perceived by the atoms.
Rydberg atoms are neutral atoms excited to high principal quantum number states, which endows them with exaggerated properties such as large electric dipole moments, long lifetimes, and extreme sensitivity to external electromagnetic fields. These characteristics form the foundation of Rydberg atom-based sensors, an emerging class of quantum devices capable of optically detecting electric fields across frequencies from DC to the terahertz regime. Rydberg-based electrometry operates through both Autler–Townes (AT) splitting of resonant Rydberg transitions and Stark-shift measurements for high-frequency or far-detuned fields, enabling broadband field sensing from DC to the THz regime. Using ladder-type electromagnetically induced transparency (EIT) and AT splitting, these sensors enable non-invasive, SI-traceable measurements of field amplitude, frequency, phase, and polarization. Recent developments have demonstrated broadband electric field probes, voltage calibration standards, and compact RF receivers based on thermal vapor cells and integrated photonic architectures. Furthermore, innovations in multi-photon EIT, superheterodyne readout, and multi wave mixing have expanded the dynamic range and bandwidth of Rydberg-based electrometry. Despite challenges related to environmental perturbations, linewidth broadening, and laser stabilization, ongoing advances in atomic control, hybrid photonic integration, and EIT-based readout promise scalable, chip-compatible sensors. This review summarizes the physical principles, experimental progress, and emerging applications of Rydberg atom-based sensing, emphasizing their potential for next generation quantum metrology, wireless communication, and precision field mapping.
Atom in Rydberg state has large polarizability, large electric dipole and low ionization threshold field. It is very sensitive to electric field, therefore it can be used to measure the amplitude of electric field, especially the microwave electric field. The new developed scheme is based on quantum interference effects (electromagnetically induced transparency and Autler-Townes splitting) in Rydberg atoms. Instead of the direct amplitude measurement, this method tests the Rabi frequency value of the transmission spectrum which is determined by the microwave electric field strength and the corresponding atom nature. The minimum measured strengths of microwave electric fields are far below the standard values obtained by traditional antenna methods. Compared with the traditional methods, this new scheme has several advantages, such as self-calibration, non-perturbation to the measured field and independence of the probe length. Besides, this scheme can also be used to measure the polarization direction of microwave electric field and realize sub-wavelength imaging. Through adjusting the wavelength of coupling laser, a broadband 1-500 GHz microwave electric field measurement can be achieved. This new scheme is benefitial to conducting the continue electric field measurement and the miniaturization of the test equipment. In this paper, the researches about using Rydberg atom to measure electric field with high precision are reviewed. The basic theory and experimental techniques are introduced. Finally, we discuss a promising method of using Rydberg atom interferometer to detect the accumulated phase in the process of interaction between electric field and Rydberg atoms. This method converts amplitude measurement into phase test, which may improve the precision and sensitivity.