We describe experiments relevant to Rydberg atom-based sensing. In Rydberg atom-based sensing, atoms contained in a vapor cell are used as a probe of an incident radio frequency electric field. We present a novel approach based on a collinear three-photon read-out and detection scheme, which extends the sensing range of the self-calibrated Autler-Townes sensing mode to lower electric field strengths. We demonstrate proof of concept and present concrete results from first experiments. We show that we are able to measure electric field strengths below 1 mV/cm in the self-calibrated Autler-Townes regime for a radial dipole moment of 2206 ea0for a transition at 10.7 GHz. We measure an Autler-Townes splitting of 503(6) kHz, which is equivalent to a radio frequency electric field strength of micro-V/cm.
We describe experiments relevant to Rydberg atom-based sensing. In Rydberg atom-based sensing, atoms contained in a vapor cell are used as a probe of an incident radio frequency electric field. We present a novel approach based on a collinear three-photon read-out and detection scheme, which extends the sensing range of the self-calibrated Autler-Townes sensing mode to lower electric field strengths. We demonstrate proof of concept and present concrete results from first experiments. We show that we are able to measure electric field strengths below 1 mV/cm in the self-calibrated Autler-Townes regime for a radial dipole moment of 2206 ea0for a transition at 10.7 GHz. We measure an Autler-Townes splitting of 503(6) kHz, which is equivalent to a radio frequency electric field strength of micro-V/cm.
We have shown that Rydberg atoms can be used for high-sensitivity, absolute sensing of radio frequency (RF) electric fields. We achieved a sensitivity of 3 μVcm-1Hz-1/2 for two read-out strategies. Results using a Mach-Zehnder interferometer2 and frequency modulated spectroscopy both achieve similar photon shot noise limited sensitivity. Fundamental limits to the sensitivity of the Rydberg atom-based RF electric field sensing have been addressed. Depending on the spectral resolution of the read-out, either the RF induced transmission line frequency splitting, the Autler-Townes regime, or a change in the on-resonant absorption, the amplitude regime, can be used to determine the RF electric field. Here, we present theoretical results of a 3-photon read-out scheme which enables the Autler-Townes regime of Rydberg atom-based RF electrometry to be extended to lower RF electric field strengths. We show that the residual Doppler shifts can, in principle, be reduced to ~11.8 kHz, on the order of the Rydberg atom natural lindewidths, using the approach.
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.
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.
In this work, we present a high-sensitivity, all-optical, atom-based radio-frequency electrometry technique, implemented via a collinear three-photon excitation scheme in a room-temperature cesium vapor cell. By employing a wave-vector matching condition unique to cesium, our approach reduces the residual Doppler broadening so that it does not dominate the electromagnetically induced absorption linewidth, achieving linewidths below 200 kHz. The narrow linewidth enables the expansion of the self-calibrated Autler-Townes sensing regime and increased sensitivity when compared to methods where Doppler broadening dominates the linewidth. In this paper, we report our latest sensitivity measurements which successfully detected radio-frequency (RF) Rabi frequencies of 2π×43 kHz using a 480 kHz measurement bandwidth at 10.7 GHz, corresponding to a sensitivity of 45 nV/cm/ √ Hz. The results of our experiment show a thirteen-fold improvement compared to our previously reported findings for all-optical atom-based electrometry. Our measurements demonstrate the ability to detect time-varying signals suitable for radar and communication applications with high sensitivity.
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 demonstrate Rydberg atom-based radio frequency sensing with a colinear three-photon scheme in a room temperature cesium vapor cell that minimizes residual Doppler broadening of the probe laser absorption feature. A sub-200 kHz spectral linewidth is observed and extends the self-calibrated Autler-Townes sensing regime to weaker fields by a factor of ~18 compared to the theoretical limit of the most commonly used two-photon scheme. The sensitivity of the method to microsecond pulses is shown to be sufficient to detect radio frequency Rabi frequencies of 2π x 0.44 MHz using a 480 kHz bandwidth at 108.9 GHz, demonstrating the ability to sense time-dependent signals suitable for radar and communications.