Low-frequency (LF) electric-field measurements with Rydberg atoms are limited by alkali-induced cell-surface screening and excess laser-intensity noise. Here, we address these limitations using a Cs vapor cell with built-in parallel electrodes, active laser-power stabilization, and a home-built balanced detector to suppress 10 Hz-kHz intensity noise. A 15 kHz local-oscillator field is introduced to up-convert Hz-scale signals to the lower-noise kHz band through Rydberg atom-mediated sum-frequency mixing (SFM), improving the optical readout signal-to-noise ratio. The system achieves a minimum detectable electric field of 190 nV/cm within 0.5 Hz-1.006 kHz, a linear dynamic range exceeding 67 dB, and a spectral resolution of 18 mHz.
Low-frequency (LF) electric-field measurements with Rydberg atoms are limited by alkali-induced cell-surface screening and excess laser-intensity noise. Here, we address these limitations using a Cs vapor cell with built-in parallel electrodes, active laser-power stabilization, and a home-built balanced detector to suppress 10 Hz-kHz intensity noise. A 15 kHz local-oscillator field is introduced to up-convert Hz-scale signals to the lower-noise kHz band through Rydberg atom-mediated sum-frequency mixing (SFM), improving the optical readout signal-to-noise ratio. The system achieves a minimum detectable electric field of 190 nV/cm within 0.5 Hz-1.006 kHz, a linear dynamic range exceeding 67 dB, and a spectral resolution of 18 mHz.
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.
Fields with frequencies below megahertz are challenging for Rydberg-atom-based measurements, due to the low-frequency electric field screening effect caused by the alkali-metal atoms adsorbed on the inner surface of the container. In this paper, we investigate electric field measurements in the ultralow frequency (ULF), very low frequency (VLF), and low frequency (LF) bands in a Cs vapor cell with built-in parallel electrodes. With optimization of the applied DC field, we achieve high-sensitive detection of the electric field at frequencies of 1 kHz, 10 kHz, and 100 kHz based on the Rydberg-atom sensor, with the minimum electric field strength down to 18.0 μV/cm, 6.9 μV/cm, and 3.0 μV/cm, respectively. The corresponding sensitivity is 5.7 μV/cm/Hz 1/2 , 2.2 μV/cm/Hz 1/2 , and 0.95 μV/cm/Hz 1/2 for the ULF, VLF, and LF fields, which is better than a 1-cm dipole antenna. Besides, the linear dynamic range of the Rydberg-atom sensor is over 50 dB. This work presents the potential to enable more applications that utilize atomic sensing technology in the ULF, VLF, and LF fields.
Rydberg-assisted atomic electrometry using alkali-metal atoms contained inside a vacuum environment for detecting external electric fields at frequencies below a few kilohertz has been quite challenging due to the low-frequency electric-field-screening effect that is caused by the alkali-metal atoms adsorbed on the inner surface of the container. We report a very slow electric-field-screening phenomenon with a time scale up to the order of seconds on a rubidium-vapor cell that is made of monocrystalline sapphire. Using this sapphire rubidium-vapor cell with an optically induced, internal bias electric field, we demonstrate vapor-cell-based, low-frequency atomic electrometry that responds to the electric field strength linearly. Limited by the given experimental conditions, this demonstrated atomic electrometer uses an active volume of 11mm3 and delivers a spectral noise floor of around 0.34mV/mHz and a 3-dB low cutoff frequency of around 770 Hz inside the vapor cell. This work investigates a regime of vapor-cell-based atomic electrometry that was seldom studied before, which may enable more applications that use atomic electric-field-sensing technology.
Fields with frequencies below megahertz are challenging for Rydberg-atom-based measurements, due to the low-frequency electric field screening effect that is caused by the alkali-metal atoms adsorbed on the inner surface of the container. In this paper, we investigate on electric fields measurements in the ULF, VLF and LF bands in a Cs vapor cell with built-in parallel electrodes. With optimization of the applied DC field, we achieve high-sensitive detection of the electric field at frequencies of 1kHz, 10kHz and 100kHz based on Rydberg-atom sensor, with the minimum electric field strength down to 18.0μV/cm, 6.9μV/cm and 3.0μV/cm, respectively. The corresponding sensitivity is 5.7 μV/cm/{\sqrt{Hz}}, 2.2μV/cm/{\sqrt{Hz}} and 0.95μV/cm/{\sqrt{Hz}} for ULF, VLF and LF fields, which is better than 1-cm dipole antenna. Besides, the linear dynamic range of Rydberg-atom sensor is over 50 dB. This work presents the potential to enable more applications that utilize atomic sensing technology in ULF, VLF and LF fields.
Rydberg-atom electric field sensing has shown great potential from near-DC to THz with state-of-the-art measurement metrics realized in sensitivity, phase extraction, multi-band receptivity, etc. While Rydberg-atom sensors have shown exceptional performance in the GHz regime, low-frequency operation has remained challenging because of electric-field-screening in conventional vapor cells, which suppresses externally applied fields. We overcome this limitation by combining auxiliary modulation and lock-in detection with a paraffin-coated vapor cell, and demonstrate an electrode-free, wideband method for sensing frequencies, ranging from 0.5 Hz to 10 kHz. Our work extends Rydberg-atom sensor range to VLF, ULF, SLF, ELF and sub-ELF frequency bands. In our method, high state-of-the-art sensitivities have been achieved - 819 μV/cm/Hz for 1 Hz, 33 μV/cm/Hz for 10 Hz, 10 μV/cm/Hz for 100 Hz and 2 μV/cm/Hz for 1 kHz.
We present a method for performing low-frequency electric-field sensing via ionization detection of Rydberg atoms in a collimated atomic beam. A collimated beam avoids many of the electric-field screening effects that are common in warm vapor cells due to the accumulation of alkali-metal atoms on glass surfaces. Further, a beam facilitates a spatially separated region for high signal-to-noise readout via ionization detection. Using this approach, we measure dc Stark shifts from external fields with frequencies as low as 1 Hz. The sensor demonstrates a sensitivity of better than 1 mV / m Hz for frequencies above 20 Hz and 0.14(4) mV / m Hz above 500 Hz with a linear dynamic range of over 50 dB.