Acta Photonica Sinica, Volume. 52, Issue 4, 0426001(2023)
Estimation of Rydberg Atomic State Population Excited by Two-photon Resonance
Alkali atom vapor cells are the essential component of quantum microwave measurement equipment. By means of laser pumping technology, alkali atoms can be easily excited from the ground to Rydberg states. Alkali atoms is very sensitive to electric filed because of their very large polarizability, huge electric dipole and low ionization threshold field and so on. Recently, by virtue of the strong interaction of microwave field and Rydberg atoms, alkali atom vapor cells have been widely applied to detect the amplitude, frequency, phase and polarization of electric field, especially the microwave electric field. Quantum microwave measurement technology has shown significant advantages, such as the break of probe size independent of wavelength, extremely high sensitivity and accuracy, very broad spectrum measurement, and very large dynamic range. In the past decade, the technology has shown great potential for application in the monitoring of ultra wide band electromagnetic spectrum, the metering of microwave electric field, microwave imaging and communication, etc. Thereinto, the state population of Rydberg atoms in vapor cell is one of the decisive factors affecting measurement capability. Up to now, certain properties of vapor cell can be obtained by optical or other measurement technologies, such as the thickness, refractive index and transmittance of glass envelope, atomic ratio and density in vapor cells. However, all of them can not directly reflect the Rydberg atomic states in vapor cell, which could give rise to difficulties to the performance optimization of quantum measuring equipment based on atom vapor cells. In this paper, a theoretical calculation model of Rydberg atomic state population excited by two-photon resonance has been established by using the ideal gas state equation, and the Rydberg blockade effect and gas atomic distribution are comprehensively analyzed. Meanwhile, an estimation method of Rydberg atomic state population, which is acomplished by aid of optimal Electromagnetically Induced Transparency (EIT) signal of Rydberg atoms, has been proposed and demonstrated experimentally under shading condition and room temperature, by means of the cylindrical (~1.0 cm in diametre and length) and cuboid (~1.0 cm in width and height, and ~2.0 cm in length) vapor cell, respectively. The vapor cells are filled with saturated cesium (133Cs) atoms at 300 K, and the intensity of pressure is ~6 666.1 Pa. In order to obtain the theoretical calculated and experimental estimates of the Rydberg state population excited by two-photon resonance, the EIT experimental setup has been put up by ~852 nm and ~1 020 nm semiconductor laser. Both of them are produced by TOPTICA Photonics. The typical spectral linewidths (5 μs integration time) of two semiconductor lasers are ~100 kHz. The ~852 nm laser, which is stabilized on the saturated absorption spectral signal of 133Cs D2-line, is employed as a probe laser to irradiate into the vapor cells to excite the 133Cs atoms from the ground state (
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Qiang AN, Chengjing LIU, Kai YANG, Jiawei YAO, Bo WU, Yi LIN. Estimation of Rydberg Atomic State Population Excited by Two-photon Resonance[J]. Acta Photonica Sinica, 2023, 52(4): 0426001
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Received: Sep. 26, 2022
Accepted: Nov. 2, 2022
Published Online: Jun. 21, 2023
The Author Email: LIN Yi (linyi13@nudt.edu.cn)