In this work, Electromagnetically Induced Transparency (EIT) has been studied in a RF-driven four-level ladder85Rb atomic model. Rb atomic cell is simultaneously driven by three fields; two lasers, namely control and probe and one microwave. This spectroscopic technique of exposing atomic vapors to three energies may get established as a quantum primary standard for the RF electric-field amplitude metrology due to its dependency only on universal Plank's constant. It is observed that when right resonant frequency is achieved the absorption spectrum gives a transition to EIT by inducing a window in middle of the curve cancelling the absorption. In addition, two-dimensional localization of an atom is also studied in various field scenarios. The maxima of absorption spectrum can be modified by making slight modifications in the electromagnetic fields driving the system. Next step in the metrology would be of measuring vector E-field for which finding the position of an atom may play a crucial role. This may add one extra degree of freedom in the evaluation of SI traceable E-field.
In this work, Electromagnetically Induced Transparency (EIT) has been studied in a RF-driven four-level ladder85Rb atomic model. Rb atomic cell is simultaneously driven by three fields; two lasers, namely control and probe and one microwave. This spectroscopic technique of exposing atomic vapors to three energies may get established as a quantum primary standard for the RF electric-field amplitude metrology due to its dependency only on universal Plank's constant. It is observed that when right resonant frequency is achieved the absorption spectrum gives a transition to EIT by inducing a window in middle of the curve cancelling the absorption. In addition, two-dimensional localization of an atom is also studied in various field scenarios. The maxima of absorption spectrum can be modified by making slight modifications in the electromagnetic fields driving the system. Next step in the metrology would be of measuring vector E-field for which finding the position of an atom may play a crucial role. This may add one extra degree of freedom in the evaluation of SI traceable E-field.
We investigate the relationship between the Rabi frequency (ΩRF, related to the applied electric field) and Autler-Townes (AT) splitting, when performing atom-based radio-frequency (RF) electric (E) field strength measurements using Rydberg states and electromagnetically induced transparency (EIT) in an atomic vapor. The AT splitting satisfies, under certain conditions, a well-defined linear relationship with the applied RF field amplitude. The EIT/AT-based E-field measurement approach derived from these principles is currently being investigated by several groups around the world as a means to develop a new SI-traceable RF E-field measurement technique. We establish conditions under which the measured AT-splitting is an approximately linear function of the RF electric field. A quantitative description of systematic deviations from the linear relationship is key to exploiting EIT/AT-based atomic-vapor spectroscopy for SI-traceable field measurement. We show that the linear relationship is valid and can be used to determine the E-field strength, with minimal error, as long as the EIT linewidth is small compared to the AT-splitting. We also discuss interesting aspects of the thermal dependence (i.e., hot- versus cold-atom) of this EIT-AT technique. An analysis of the transition from cold- to hot-atom EIT in a Doppler-mismatched cascade system reveals a significant change of the dependence of the EIT linewidth on the optical Rabi frequencies and of the AT-splitting on ΩRF.
Rydberg atoms efficiently link photons between the radio-frequency (rf) and optical domains. They furnish a medium in which the presence of an rf field imprints on the transmission of a probe laser beam by altering the coherent coupling between atomic quantum states. The immutable atomic energy structure underpins quantum-metrological rf-field measurements and has driven intensive efforts to realize inherently self-calibrated sensing devices. Here, we investigate spectroscopic signatures owing to the quantization of atomic angular momentum. Using an electromagnetically induced transparency (EIT) sensing scheme, specific combinations of atomic terms are shown to give rise to universal, distinctive fingerprints in the detected optical fields upon rotating a linearly polarized rf field. Employing a dressed state picture, we identify two types of atomic angular momentum ladders that display strikingly disparate spectroscopic characteristics, including the distinctive absence or presence of a central spectral EIT peak. Our study adds important insights into the prospects of Rydberg atomic gases for quantum-metrological electric field characterization including polarimetry. In particular, it calls into question prevailing interpretations of SI-traceable Rydberg atom electrometers.
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 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.
Abstract We study electromagnetically induced transparency (EIT) in a room-temperature cesium vapor cell using wavelength-modulated probe laser light. In the utilized cascade level scheme, the probe laser drives the lower transition 6 S 1 / 2 ( F = 4) → 6 P 3 / 2 ( F ’ = 5), while the coupling laser drives the Rydberg transition 6 P 3 / 2 → 57 S 1 / 2 . The probe laser has a fixed average frequency and is modulated at a frequency of a few kHz, with a variable modulation amplitude in the range of tens of MHz. The probe transmission is measured as a function of the detuning of the coupling laser from the Rydberg resonance. The first-harmonic demodulated EIT signal has two peaks that are, in the case of large modulation amplitude, separated by the peak-to-peak modulation amplitude of the probe laser times a scaling factor λ p / λ c , where λ p and λ c are the probe- and coupling-laser wavelengths. The scaling factor is due to Doppler shifts in the EIT geometry. Second-harmonic demodulated EIT signals, obtained with small modulation amplitudes, yield spectral lines that are much narrower than corresponding lines in the modulation-free EIT spectra. The resultant spectroscopic resolution enhancement is conducive to improved measurements of radio-frequency (RF) fields based on Rydberg-atom EIT, an approach in which the response of Rydberg atoms to RF fields is exploited to characterize RF fields. Here, we employ wavelength modulation spectroscopy to reduce the uncertainty of atom-based frequency and field measurement of an RF field in the VHF radio band.
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.