Broadband Rydberg atom based self-calibrating RF E-field probe
Christopher L. Holloway, Josh A. Gordon, Andrew Schwarzkopf, Dave Anderson, Stephanie Miller, Nithiwadee Thaicharoen, Georg A. Raithel, Steven R. Jefferts, Thomas P. Heavner
We present a significantly new approach for an electric (E) field probe design. The probe is based on the interaction of RF-fields with Rydberg atoms, where alkali atoms are excited optically to Rydberg states and the applied RF-field alters the resonant state of the atoms. For this probe, the Rydberg atoms are excited in a glass vapor cell. The Rydberg atoms act like an RF-to-optical transducer, converting an RF E-field to an optical-frequency response. The probe utilizes the concept of Electromagnetically Induced Transparency (EIT). The RF transition in the four-level atomic system causes a split of the EIT transmission spectrum for the probe laser. This splitting is easily measured and is directly proportional to the applied RF field amplitude. Therefore, by measuring this splitting we get a direct measurement of the RF E-field strength. The significant dipole response of Rydberg atoms over the GHz regime enables this technique to make traceable measurements over a large frequency band including 1-500 GHz. We will show that, with one probe, measurements can be made over a very large frequency range. This is a truly broadband probe/sensor. In this paper, we report on our results in the development of this probe.
We present a significantly new approach for an electric (E) field probe design. The probe is based on the interaction of RF-fields with Rydberg atoms, where alkali atoms are excited optically to Rydberg states and the applied RF-field alters the resonant state of the atoms. For this probe, the Rydberg atoms are excited in a glass vapor cell. The Rydberg atoms act like an RF-to-optical transducer, converting an RF E-field to an optical-frequency response. The probe utilizes the concept of Electromagnetically Induced Transparency (EIT). The RF transition in the four-level atomic system causes a split of the EIT transmission spectrum for the probe laser. This splitting is easily measured and is directly proportional to the applied RF field amplitude. Therefore, by measuring this splitting we get a direct measurement of the RF E-field strength. The significant dipole response of Rydberg atoms over the GHz regime enables this technique to make traceable measurements over a large frequency band including 1-500 GHz. We will show that, with one probe, measurements can be made over a very large frequency range. This is a truly broadband probe/sensor. In this paper, we report on our results in the development of this probe.
In this presentation, we discuss a fundamentally new approach for an electric (E) field probe design. This new approach is significantly different than currently used field probes in that it is based on the interaction of RF-fields with Rydberg atoms (alkali atoms placed in a glass vapor cell are excited optically to Rydberg states). The applied RF-field alters the resonant state of the atoms. The Rydberg atoms act like an RF-to-optical transducer, converting an RF E-field to an optical-frequency response. The RF probe utilizes the concept of Electromagnetically Induced Transparency (EIT). The RF transition in the four-level atomic system causes a split of the EIT transmission spectrum for a probe laser. This splitting is easily measured and is directly proportional to the applied RF field amplitude. The significant dipole response of Rydberg atoms enables this technique to make self-calibrating measurements over a large frequency band including 1-500 GHz. In this paper, we report on our results in the development of this probe. We also discuss two key applications: that is, self-calibrated measurements and sub-wavelength imaging and field mapping.
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.
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.
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.
Atomic sensing and electric field measurements based on the use of the all-optical electromagnetic induction transparency (EIT) spectrum of Rydberg atoms have attracted great interest due to the advantages of self-calibration, Le Système International d'unités traceability, and a broadband spectrum. At the same time, this methodology also promotes the development of atomic sensor technology. We present a novel high-efficiency Rydberg-atom radio-frequency (RF) electric (E) field integrated probe (Rydberg Field Probe or RFP). The high-efficiency RFP consists of a 10 mm cubic 133Cs vapor cell, a dichroic mirror, three collimating lenses, and three fibers. This system can be used to independently control two counterpropagating lasers passing through a vapor cell, easing the design effort. In addition, the overall system efficiency can reach a value of 40.4%, reducing the EIT power broadening doe conventional RFPs. Based on the designed high-efficiency RFP, near-field electric field measurement and imaging of a C-band horn antenna at 4.48 GHz are performed by using the resonant RF field of the 133Cs atomic Rydberg state at room temperature with a spatial resolution of λ/6. These results promote the development of atomic sensing technology and show great application potential for the measurement of measuring high-resolution radio frequency electric fields and arrays of RFPs.
Atom-based radio-frequency (RF) electric field probes have the potential to improve electric field measurements for a broad range of frequencies (from a few GHz to 100s of GHz) and field strengths (mV/m to kV/m). For these probes to become a common measurement method, their range must be extended to high frequency (>100 GHz) and low field strength regimes. We present SI-traceable electric field measurements of RF fields above 100 GHz, using Autler-Townes splitting of Rydberg electromagnetically-induced transparency in a rubidium (Rb) vapor. We also demonstrate several techniques, including RF detuning from resonance and enhanced absorption, for increasing the probe sensitivity.