International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)
THz electrometry with Rydberg atoms and all IR lasers
Shuying Chen, Dominic J. Reed, Lucy A. Downes, Andrew R. MacKellar, Nourah F. A. Almuhawish, Matthew J. Jamieson, Charles S. Adams, Kevin J. Weatherill
Rydberg electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting in an atomic vapor cell can be used as novel methods for electric-magnetic field detection. Here we make use of 3 infrared lasers to realize a Rydberg EIT system in a thermal rubidium vapor cell. With the AT splitting induced by the THz radiation, we observe a linear trend between THz field amplitude and the frequency splitting of the absorption dips and EIT transmission peaks. Due to the well-known atomic transition dipole moment of the Rydberg state, the THz electric field can be calibrated from the frequency splitting, making this Rydberg atomic measurement system a practical tool for THz field detection.
Rydberg electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting in an atomic vapor cell can be used as novel methods for electric-magnetic field detection. Here we make use of 3 infrared lasers to realize a Rydberg EIT system in a thermal rubidium vapor cell. With the AT splitting induced by the THz radiation, we observe a linear trend between THz field amplitude and the frequency splitting of the absorption dips and EIT transmission peaks. Due to the well-known atomic transition dipole moment of the Rydberg state, the THz electric field can be calibrated from the frequency splitting, making this Rydberg atomic measurement system a practical tool for THz field detection.
We discuss a fundamentally new method for electric (E) field strength (V/m) metrology applicable to the near-field. This new approach is significantly different from currently used field measurement techniques in that it is based on the interaction of radio-frequency (RF) E-fields with Rydberg atoms (alkali atoms placed in a glass vapor cell that are excited optically to Rydberg states). The applied RF E-field alters the state of the atoms. The Rydberg atoms act like an RF-to-optical transducer, converting an RF E-field strength to an optical-frequency response. In this new approach, we employ the phenomena of electromagnetically induced transparency (EIT) and Autler-Townes splitting. The RF transition in the four-level atomic system causes a split of the EIT transmission spectrum of a probe laser into two peaks. This splitting is easily measured and is directly proportional to the applied RF E-field amplitude. The significant dipole response of Rydberg atoms enables this technique to make self-calibrating measurements over a large frequency band including 500 MHz to 500 GHz (and possibly up to 1 THz and down to 10s of megahertz). In this paper, we report on our results in the development of this metrology approach, including the first fiber-coupled vapor-cell for E-field measurements. We also discuss key applications, including self-calibrated measurements, millimeter-wave and sub-THz measurements, field mapping, and sub-wavelength and near-field imaging. We show results for mapping the fields inside vapor cells, for measuring the E-field distribution along the surface of a circuit board, and for measuring the near-field at the aperture in a cavity. We also discuss the uncertainties of this measurement technique.
We provide the simultaneous traceable measurements of microwave electric fields at two different frequencies by the electromagnetically induced transparency (EIT) and Autler–Townes (AT) splitting. A static magnetic field working together with a linearly polarized probe and coupling light prepares Rydberg atoms in Zeeman sublevels with maximal |mJ| in an atomic vapor cell. Using the EIT-AT splitting of these two maximal |mJ| states, the microwave electric fields at two different frequencies are simultaneously measured, in which their frequency difference can be adjustable within the linear range of magnetic field-induced level shifts. The proposed method provides a promising prospect for calibrating multiple microwave frequencies simultaneously in the future.
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.
To isolate the Autler-Townes splitting induced by a single selected THz transition in a Cs Rydberg atom, a Zeeman-resolved EIT (electromagnetically induced transparency) signal was obtained in a high magnetic field. The electronic state was controlled by the polarizations of two lasers exciting the Cs atoms and the chosen magnetic quantization axis. Applying a THz wave with controlled polarization then enabled an observation of the Autler-Townes splitting induced by its coupling to a single dipole transition.
In recent years, terahertz (THz) technology has made significant progress in numerous applications; however, the highly sensitive, room-temperature THz detectors are still rare, which is one of the bottlenecks in THz research. In this paper, we proposed a room-temperature electrometry method for THz detection by laser spectroscopy of cesium ( Cs 133) Rydberg atoms, and conducted a comprehensive investigation of the five-level system involving electromagnetically induced transparency (EIT), electromagnetically induced absorption (EIA), and Autler–Townes (AT) splitting in Cs 133 cascades. By solving the Lindblad master equation, we found that the influence of the THz electric field, probe laser, dressing laser, and Rydberg laser on the ground state atomic population as well as the coherence between the ground state and the Rydberg state, plays a crucial role in the transformation and amplitude of the EIT and EIA signals. Temperature and the atomic vapor cell’s dimensions affect the number of Cs 133 atoms involved in the detection, and ultimately determine the sensitivity. We predicted the proposed quantum coherence THz detection method has a remarkable sensitivity of as low as 10 −9 V m −1 Hz −1/2 . This research offers a valuable theoretical basis for implementing and optimizing quantum coherence effects based on Rydberg atoms for THz wave detection with high sensitivity and room-temperature operation.
With the rapid advancement of terahertz (THz) technology, there is an urgent demand for highly sensitive, broadband THz detectors that can operate at room temperature to support the evolving applications. Due to the high sensitivity of Rydberg atoms to external electric fields, detectors based on Rydberg quantum coherence offer great potential for highperformance THz detection. This paper proposed a ambient temperature electrometry approach for THz detection using probe laser spectroscopy of Rb Rydberg atoms and carry out a comprehensive study of a four-level system involving electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting in Rb cascades. By solving the Lindblad master equation, the influences of the THz electric field, probe laser, and coupling laser on the populations of the ground and Rydberg states were analyzed. Furthermore, the effects of temperature and vapor cell dimensions on the Rb atomic density are examined, revealing their critical impact on detection sensitivity. The results predict that the proposed quantum coherence based THz detection method can achieve a sensitivity as low as 10−9V/m/Hz1/2at ambient temperature. This paper provides a solid theoretical foundation for the implementation and optimization of Rydbergatom- based quantum coherence techniques for high-sensitivity, ambient temperature THz wave detection.