Abstract Quantum electrometric sensing properties of a four-level system are theoretically investigated for microwave (MW) field measurement in thermal Rydberg atoms. In the considered system, the phenomenon of electromagnetically induced transparency (EIT) is invoked to study the impact of microwave (MW) field strength on its optical response. The amplitude of the MW electric field is obtained directly by measuring the height and frequency of EIT peaks. Further, for MW frequency measurement, the probe spectra are examined for red and blue MW detuned cases. It is found that the responsiveness of 133Cs for MW electric field as well as frequency is relatively higher than 87Rb. The overall sensitivity of both these atoms can be enhanced by the convenient setting of the system and field parameters.
Abstract Quantum electrometric sensing properties of a four-level system are theoretically investigated for microwave (MW) field measurement in thermal Rydberg atoms. In the considered system, the phenomenon of electromagnetically induced transparency (EIT) is invoked to study the impact of microwave (MW) field strength on its optical response. The amplitude of the MW electric field is obtained directly by measuring the height and frequency of EIT peaks. Further, for MW frequency measurement, the probe spectra are examined for red and blue MW detuned cases. It is found that the responsiveness of 133Cs for MW electric field as well as frequency is relatively higher than 87Rb. The overall sensitivity of both these atoms can be enhanced by the convenient setting of the system and field parameters.
Abstract A scheme for measuring microwave (MW) electric (E) fields is proposed based on bichromatic electromagnetically induced transparency (EIT) in Rydberg atoms. A bichromatic control field drives the excited state transition, whose absorption shows three EIT windows. When a MW field drives the Rydberg transition, the EIT windows split and six transmission peaks appear. It is interesting to find that the peak-to-peak distance of transmission spectrum is sensitive to the MW field strength, which can be used to measure MW E-field. Simulation results show that the measurement accuracy could be increased by about 4 times, and the minimum detectable strength of the MW E-field may be improved by about 3 times compared with the common EIT scheme. After the Doppler averaging, the minimum detectable MW E-field strength is about 5 times larger than that without Doppler effect. Also, we investigate other effects on the sensitivity of the system.
A scheme for the measurement of a microwave (MW) electric field is proposed via multi-photon coherence in Rydberg atoms. It is based on the three-photon electromagnetically induced absorption (TPEIA) spectrum. In this process, the multi-photon produces a narrow absorption peak, which has a larger magnitude than the electromagnetically induced transparency (EIT) peak under the same conditions. The TPEIA peak is sensitive to MW fields, and can be used to measure MW electric field strength. We found that the magnitude of TPEIA peaks shows a linear relationship with the MW field strength. The simulation results show that the minimum detectable strength of the MW fields is about 1/10 of that based on an common EIT effect, and the probe sensitivity could be improved by about four times. Furthermore, the MW sensing based on three-photon coherence seems to be robust against the changes in the control field and shows a broad tunability, and the scheme may be useful for designing novel MW sensing devices.
An enhanced measurement of the microwave electric (MW E) field by using intracavity Rydberg atoms is proposed. Based on electromagnetically induced transparency (EIT), the intracavity atomic system exhibits two EIT windows, resulting in two narrow peaks in the cavity transmission. The peak-to-peak distance is sensitive to MW fields and can be used to probe MW E-field strength. Simulation results show that the detectable minimum strength of the MW fields is nearly eight times smaller than that without a cavity. Due to cavity coupling, the transmission spectrum is greatly narrowed, which improves the measurement resolution substantially. The numerical results show that the spectrum resolution is increased by more than 20 times. Furthermore, the cavity-enhanced measurement scheme seems to be robust against the changes in the control field strength and shows a broadband tunability.
Abstract We present a mechanism for improving the sensitivity of microwave (MW) electric field (E-field) measurement using dual-MW-dressed electromagnetically induced transparency in a 5 S 1/2 –5 P 3/2 –56 D 5/2 –57 P 3/2 85 Rb atomic coherent system. An auxiliary MW (A-MW) field is introduced into the MW E-field measurement system, which consists of a probe, coupling lasers, and a target MW (T-MW) field. When the A-MW field frequency is tuned to be the same as the T-MW field and its power is adjusted to a suitable range, the T-MW field strength can be read out effectively. Finally, the sensitivity of MW E-field measurement is improved by about two orders of magnitude compared to that without an A-MW field. In addition, this mechanism is proven to be applicable for all frequency bands covered by Rydberg energy levels. This work opens up a novel pathway for the realization of high-sensitivity MW E-field measurement with Rydberg atoms.
The Rydberg-based microwave detection is an all-optical technology that uses the strong coherent interaction between Rydberg atoms and microwave field. Different from the traditional microwave meter, the Rydberg atomic sensing is a new-type microwave detector that transforms the microwave spectrum into a coherent optical spectrum, and arouses increasingly the interests due to its high sensibility. For this kind of sensor, the coherence effect induced by coupling atoms with microwave plays a key role, and the decoherence may reduce the sensitivity. A multi-level Rydberg atomic scheme with optimized quantum coherence, which enhances both the bandwidth and the sensitivity for 4 GHz microwave sensing, is demonstrated experimentally in this work. The enhanced quantum coherence of Rydberg electromagnetically induced transparency (EIT) and microwave induced Autler-Townes (AT) splitting in EIT windows are shown using optical pumping at D1 line. The enhanced sensitivity at 3.4 GHz with 0.3 GHz bandwidth can be realized, based on the enhanced EIT-AT spectrum. The experimental results show that in the stepped Rydberg EIT system, the spectral width of EIT and microwave field EIT-AT can be narrowed by optical pumping (OP), so the sensitivity of microwave electric field measurement can be improved. After optimizing the EIT amplitude and adding single-frequency microwaves, the sensitivity of the microwave electric field measurement observed by the AT splitting interval is improved by 1.3 times. This work provides a reference for utilizing atomic microwave detection.
Significant progress has been made in atom-based measurements of length, time, gravity and electromagnetic fields in recently years. Rydberg atom-based microwave electric field measurement, using electromagnetically induced transparency (EIT) in room temperature alkali-metal vapors, has been extensively investigated and aroused the broad interest. This approach may establish a new standard for the measurements of microwave (MW) and radio frequency (RF) electric fields.In this review, we describe the work on a new method of measuring electric fields based on quantum interference by using either cesium or rubidium atoms contained in a dielectric vapor cell. Rydberg atoms with principal quantum number n >>1 have large direct current (DC) polarizabilities and microwave transition dipole moments, thereby making them extremely sensitive to external electric fields. Using the Rydberg three-level EIT to detect the level splitting and shift that is induced by the external field, we can realize a rapid and robust self-calibration method of measuring the electric field in a frequency range from 0.01 GHz to 1000 GHz. For the MW electric field (frequency range > 1 GHz), the MW field causes the Rydberg states to split, known as an Autler-Townes splitting (A-T) effect when the applied microwave can resonate with adjacent Rydberg states. The MW coupled A-T splitting is proportional to the applied electric field strength, from which the field strength is measured. Using the EIT window, a high sensitivity of 3 μV·cm-1·Hz-1/2 and small electric field of 1 μV/cm are expected to be achieved with a modest setup, and the limitations of the sensitivity are also addressed in the review. For the RF field at frequency mj EIT lines, and avoided crossings formed with the fine-structure levels of equal mj and different J's, which is used to calibrate and measure the RF field amplitude. On the other hand, the dependence of the EIT-line strength on the RF field polarization provides a fast and robust polarization measurement of RF fields based on matching experimental data with a theoretical simulation. The measurements of minimum strengths and sensitivity of RF fields based on Rydberg atoms are one order magnitude below the values obtained by traditional antenna methods. The atom-based field measurement paves the way for determining fields through calibration-free, invariable atomic properties and miniaturization. We also propose its various potential applications in the future.