Rydberg atomic receiver holds distinctive advantages of ultra-wide operating bandwidth and inherently high sensitivity in electric field measurement 1 , in particular, it promises unique superiority of miniaturization for low-frequency especially kHz-band signals, which hold pivotal value in applications such as long-range navigation, ground-penetrating radar, and underwater communication. However, the capability of kHz atomic receivers remains severely constrained by the shielding effects of adsorbed alkali metal atoms. Here, we propose a conceptually new self-dressing kHz signal measurement paradigm by converting the undesired coupling-laser-induced DC field to an atomic dressing, and deftly building atomic superheterodyne inside the sapphire vapor cell, which is prepared to adequately suppress the low-frequency shielding through resistivity manipulation engineering. Further, we realize strengthened interaction between the atoms and kHz field by localized enhancement of the incident signals, and finally achieve an ultrahigh sensitivity of 13.5 nV/cm/Hz 1/2 at 100 kHz. This architecture represents a significant advance, with the potential to greatly accelerate the practical applications of Rydberg atomic receivers in kHz-band detection, communication, and related fields.
Rydberg atomic receiver holds distinctive advantages of ultra-wide operating bandwidth and inherently high sensitivity in electric field measurement 1 , in particular, it promises unique superiority of miniaturization for low-frequency especially kHz-band signals, which hold pivotal value in applications such as long-range navigation, ground-penetrating radar, and underwater communication. However, the capability of kHz atomic receivers remains severely constrained by the shielding effects of adsorbed alkali metal atoms. Here, we propose a conceptually new self-dressing kHz signal measurement paradigm by converting the undesired coupling-laser-induced DC field to an atomic dressing, and deftly building atomic superheterodyne inside the sapphire vapor cell, which is prepared to adequately suppress the low-frequency shielding through resistivity manipulation engineering. Further, we realize strengthened interaction between the atoms and kHz field by localized enhancement of the incident signals, and finally achieve an ultrahigh sensitivity of 13.5 nV/cm/Hz 1/2 at 100 kHz. This architecture represents a significant advance, with the potential to greatly accelerate the practical applications of Rydberg atomic receivers in kHz-band detection, communication, and related fields.
High-sensitivity amplitude and frequency detection of microwave electric fields is of significant importance in various fields, including communications, microwave quantum technology, aerospace, medicine, and meteorology. Rydberg atom-based sensors promise traceable standards and high sensitivity for detecting weak electric fields and enhancing sensing sensitivity, mainly by using superheterodyne technology and resonant structures. Detecting high-frequency (HF) band fields with high sensitivity using Rydberg atom sensors is a significant challenge due to the requirement of exciting atoms to extremely high energy states for resonant detection. We demonstrate the off-resonant Rydberg atomic superheterodyne architecture with additional resonators for greatly enhancing the sensing sensitivity to HF band fields. In this approach, we propose a miniaturized square spiral resonator with an electrical size of$0.011~\lambda $at 15.54 MHz. To reduce the electric-field-screening effect of the adsorption of alkali metal atoms, we use a monocrystalline sapphire cesium (Cs) vapor cell. By utilizing the off-resonant alternating current (ac) Stark effect, the initial sensitivity of the Rydberg atom sensor without the resonator is measured to be10.39μV/cmHzat room temperature. With the addition of the miniaturized square spiral resonator, the sensitivity significantly improved to2.60nV/cmHz, which has been inaccessible so far with atomic sensors. Here, we provide an enhancement of 72 dB, which is three orders of magnitude improvement in sensitivity than when the resonator is not used. This enhancement resonator extends Rydberg atomic high-sensitivity sensing to the HF band and shows great potential, especially in shortwave radio reception.
The exploitation of sub-MHz (<1 MHz) benefits a wide range of applications like underwater vehicular communication, subsurface exploration, low-frequency navigation etc. The traditional electrical receivers in this band are either hundreds of meters long or, when miniaturized, inefficient and bandwidth-limited, making them inapplicable for practical underwater implementations. Such obstacles can be circumvented by the emerging Rydberg atomic receiving technology, which is capable of detecting fields from DC up to the terahertz regime with compact structure. Against this background, we propose a method to detect sub-MHz electric fields without further calibration. Specifically, a physics-based model of the combined DC and AC-Stark response is established. Based on the model, we modulate the DC-Stark spectrum with the received signal and extract its amplitude by fitting the cycle-averaged, symmetric Stark-split peaks. Then we map this swing directly to the intrinsic atomic polarizability. By such operations, the proposed method can remove the dependence on electrode spacing or field-amplitude references. For performance evaluation, six-level Lindblad simulations and experiments conducted at a low-frequency field of 30 kHz demonstrate a minimum detectable field of 5.3 mV/cm, with stable readout across practical optical-power variations. The approach manages to expand the operating range of Rydberg atomic receivers below 1 MHz, and enables compact, calibration-free quantum front ends for underwater and subsurface receivers.
We demonstrate the measurement of super low-frequency electric field using Rydberg atoms in an atomic vapor cell with inside parallel electrodes, thus overcoming the low-frequency electric-field-screening effect at frequencies below a few kHz. Rydberg electromagnetically induced transparency (EIT) spectra involving 52 D 5/2 state is employed to measure the signal electric field. An auxiliary DC field is applied to improve the sensitivity. A DC Stark map is demonstrated, where the utilized 52 D 5/2 exhibits m j = 1/2, 3/2, 5/2 Stark shifts and splittings. The m j = 1/2 state is employed to detect the signal field because of its larger polarizability than that of m j = 3/2, 5/2. Also, we show that the strength of the spectrum is dependent on the angle between the laser polarizations and the electric field. With optimization of the applied DC field to shift the m j = 1/2 Rydberg energy level to a high sensitivity region and the laser polarizations to obtain the maximum m j = 1/2 signal, we achieve the detection of the signal electric field with a frequency of 100 Hz down to 214.8 µ V/cm with a sensitivity of 67.9 µ V cm −1 Hz −1/2 , and the linear dynamic range is over 37 dB. Our work extends the measurement frequency of Rydberg sensors to super low frequency with high sensitivity, which has the advantages of high sensitivity and miniaturization for receiving super low frequency.
Rydberg atoms have emerged as a versatile and efficient platform for high-sensitivity quantum sensing of free-space electric fields, with remarkable progress in detecting low-frequency signals. To date, low-frequency Rydberg receivers have relied on a constant bias field, typically realized via intra-cell electrodes or Rydberg plasmas generated by photoelectric effects or inter-atomic interactions. While these approaches improve sensitivity, they suffer from inherent challenges in calibration, long-term stability, and robustness, hindering practical deployment. Here, we propose, design, and experimentally demonstrate a quantum sensing scheme for low-frequency electric signals using modulated auxiliary fields in Rydberg atoms. Unlike conventional methods that employ external DC electric fields that are often fully shielded by adsorbed atom layers on the cell walls, we introduce an AC-field modulation strategy. The incoming low-frequency signal mixes with the auxiliary field, and together they induce Stark shifts of the Rydberg level. These shifts are mapped onto the probe laser via electromagnetically induced transparency (EIT), in a manner analogous to heterodyne detection. We demonstrate a sensitivity of 7.5±2.6μV/(cm⋅Hz1/2) at 5 kHz and a minimal detectable field of 0.26±0.04μV/cm with an integration time of 1000 s. Furthermore, we extend this approach to systematically analyze the performance of generalized auxiliary fields containing multiple frequency components. By virtue of modulated auxiliary field and quantum frequency mixing, our results establish a robust and systematic framework for quantum sensing of low-frequency electric fields with Rydberg atoms, offering improved sensitivity, stability, and immunity to environmental drifts.
Highly sensitive detection of microwave (MW) fields throughout ultra-wideband spectrum is always an important subject in metrology, electromagnetism and cosmology. Rydberg atomic electrometers, which implement electric field measurements by detecting the disturbance of atomic energy levels, have the potentials to breakthrough the sensitivity and size limits of conventional sensors. However, due to the discrete structure of the energy levels, current measurements can only exhibit high sensitivity at the discontinuous frequencies which correspond to certain transitions. In this work, by implementing energy level modulation of Rydberg atom through Zeeman effect, we achieve continuous highly sensitive MW fields detection within 1-40 GHz ultra-wideband spectrum where the detection sensitivity is roundly below 65 nV cm-1 Hz-1/2, which is 2-3 orders of magnitude lower than that of the state-of-the-art continuous measurement architectures. The proposed method is expected to expand the working bandwidth from MHz to THz and therefore greatly accelerate the practical applications in the areas of radar and electronic reconnaissance. Detecting microwave fields across an ultra-wideband spectrum is crucial for advancements in metrology, electromagnetism, and cosmology. Here, the authors utilize Zeeman effect modulation of Rydberg atoms to achieve continuous, highly sensitive detection from 1-40 GHz, significantly enhancing sensitivity and potentially transforming radar and electronic reconnaissance applications.
We report several technical approaches that significantly improve the performance of a vapor-cell atomic electrometer operating in the quasi-DC frequency domain (≪ 1 kHz). With a very small active volume of approximately 11 mm3 inside the vapor cell, we demonstrated a noise floor for electric field (E-field) sensitivity ranging from 0.2 to 7.7 mV/mHz for a frequency band of 1--100 Hz. Our work utilizes only a bare vapor cell for electrometry, without any metal parts or electrodes, to ensure minimal distortion of the measured E-field and to minimize the effective sensing volume for high spatial resolution. The E-field-sensitive atomic state (Rydberg state) is excited and read out optically, maximizing the simplicity of the system design and enabling the miniaturization of quasi-DC E-field sensors for potential applications, such as diagnostics of electronics without physical contact, communications in and below the super-low frequency (SLF) band, proximity detection, remote activity surveillance, tracing charge signatures, and research in bioscience and geoscience.