We have theoretically and experimentally studied the dispersive signal of the Rydberg atomic electromagnetically-induced transparency (EIT) Autler–Townes (AT) splitting spectra obtained using amplitude modulation of the microwave (MW) electric field. In addition to the two zero-crossing points interval Δf zeros, the dispersion signal has two positive maxima with an interval defined as the shoulder interval Δf sho, which is theoretically expected to be used to measure a much weaker MW electric field. The relationship of the MW field strength E MW and Δf sho is experimentally studied at the MW frequencies of 31.6 GHz and 9.2 GHz respectively. The results show that Δf sho can be used to characterize the much weaker E MW than that of Δf zeros and the traditional EIT–AT splitting interval Δf m; the minimum E MW measured by Δf sho is about 30 times smaller than that by Δf m. As an example, the minimum E MW at 9.2 GHz that can be characterized by Δf sho is 0.056 mV/cm, which is the minimum value characterized by the frequency interval using a vapor cell without adding any auxiliary fields. The proposed method can improve the weak limit and sensitivity of E MW measured by the spectral frequency interval, which is important in the direct measurement of weak E MW.
We have theoretically and experimentally studied the dispersive signal of the Rydberg atomic electromagnetically induced transparency (EIT) - Autler-Townes (AT) splitting spectra obtained using amplitude modulation of the microwave (MW) field. In addition to the two zero-crossing points, the dispersion signal has two positive maxima with an interval defined as the shoulder interval of the dispersion signal
Δfsho. The relationship of MW field strength
EMW and
Δfsho are studied at the MW frequencies of 31.6 GHz, 22.1 GHz, and 9.2 GHz respectively. The results show that
Δfsho can be used to character the much weaker
EMW than the interval of two zero-crossing points
Δfzeros and the traditional EIT-AT splitting interval
Δfm, the minimum
EMW measured by
Δfsho is about 30 times smaller than that by
Δfm. As an example, the minimum
EMW at 9.2 GHz that can be characterized by
Δfsho is 0.056 mV/cm, which is the minimum value characterized by frequency interval using vapour cell without adding any auxiliary fields. The proposed method can improve the weak limit and sensitivity of
EMW measured by spectral frequency interval, which is important in the direct measurement of weak
EMW.
The microwave (MW) field can be measured by the Autler–Townes (AT) splitting of the electromagnetically induced transparency (EIT) spectrum in the Rydberg atomic system; however, the EIT-AT splitting method fails in weak MW fields. We used the amplitude modulation of the MW field to resolve the EIT-AT splitting in weak MW fields. The EIT-AT splitting interval can be directly obtained, and the minimum detectable MW strength is improved by six times compared with the traditional EIT-AT splitting method. The proposed method is more intuitive and convenient for measuring the strength of weak MW fields in practical applications.
The microwave electric field intensity is precisely measured by the Autler–Townes splitting of electromagnetically induced transparency spectrum in a 5S1/2−5P3/2−57D5/2−58P3/2 four-level ladder-type 85Rb atomic system. A robust multi-carrier modulation scheme is employed to improve the spectral signal-to-noise ratio, which determines the optical readout of Rydberg atom-based microwave electrometry. As a result, a factor of 2 measurement sensitivity improvement is clearly achieved compared with the on resonant Autler–Townes splitting case credit to the advantage of matched filtering. This research paves the way for building a high sensitivity, portable sensor and offers a platform for achieving compact and sensitive receiver.
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.
Atoms form the basis of precise measurement for many quantities (time, acceleration, rotation, magnetic field, etc.). Measurements of microwave frequency electric fields by traditional methods (i.e. engineered antennas) have limited sensitivity and can be difficult to calibrate properly. Highly-excited (Rydberg) neutral atoms have very large electric-dipole moments and many dipole allowed transitions in the range of 1 - 500 GHz. It is possible to sensitively probe the electric field in this range using the combination of two quantum interference phenomena: electromagnetically induced transparency and the Autler-Townes effect. This technique allows for very sensitive field amplitude, polarization, and sub-wavelength imaging measurements. These quantities can be extracted by measuring properties of a probe laser beam as it passes through a warm rubidium vapor cell. Thus far, Rydberg microwave electrometry has relied upon the absorption of the probe laser. We report on our use of polarization rotation, which corresponds to the real part of the susceptibility, for measuring the properties of microwave frequency electric fields. Our simulations show that when a magnetic field is present and directed along the optical propagation direction a polarization rotation signal exists and can be used for microwave electrometry. One central advantage in using the polarization rotation signal rather than the absorption signal is that common mode laser noise is naturally eliminated leading to a potentially dramatic increase in signal-to-noise ratio.