Power-frequency Electric Field Measurement Based On AC-Stark Effect Of Rydberg Atoms

Because the Rydberg atom's principal quantum number n(n>20)is very large and its outermost electron is weakly bound to the nucleus,it is easy to be affected by the external fields and suitable for weak electric fields sensing and measurement,especially for the precise measurement of the microwave field.The lifetime of Rydberg atom is relatively long comparing to that of ground states atom,so it has important significance in quantum precison measurement.On the one hand,it is necessary to develop a safe and stable high voltage power frequency electric field measurement technology from the viewpoints of the workers under the enviroments of the high-voltage electric fields.On the other hand,power-frequency electric field needs to be measured effectively and accurately in the fields of electric power industrial production and scientific research.Rydberg atom play a fundamental role in the research process of power frequency electric field measurement.In this paper,42D Rydberg atoms are prepared in caesium vapor at room temperature,and the electric field measurement is realized based on the electromagnetic induced transparency spectrum of Rydberg atom.In the experiment,42D Rydberg atoms were prepared by two-photon excitation method,and the stepped magnetically induced transparent spectrum was obtained by changing the coupling frequency.The relationship between the spectral shift and splitting of Rydberg atom under the RF electric field and the amplitude and frequency of the RF electric field is studied.The power frequency electric field intensity and frequency are measured by modulating the power frequency electric field amplitude to the radio frequency electric field.This paper has important reference value and significance for online traceable measurement of power frequency electric field.This paper mainly introduces the following aspects,the specific content is as follows:Chapter 1 Introduction of the definition,basic properties and application fields of Rydberg atom,as well as the background and traditional measurement methods of power-frequency electric field measurement are introduced.The development process of Rydberg atom in recent years and the main applications of electric fields sensing are briefly introduced,and the development of several power frequency electric field measurement methods and the related technical achievements are described.In the second chapter,the theoretical model of the stepped three-level EIT system is derived,and the Rydberg atom EIT effect under the RF field is analyzed.Based on the semi-classical theory of the interaction between light and atoms,the transition theory of ladder-type three-level atomic system is introduced in detail.AC-Stark frequency shift and Floquet sideband spectrum on Rydberg atomic EIT induced by RF field are described.The measuring principle of power-frequency electric field modulated in RF field is presented.In the third chapter,we introduce the main experimental system,which is the two-photon excitation system for the preparation of 42D Rydberg atom EIT and the experimental equipment for power-frequency electric field measurement.In the three-level Rydberg atom EIT system,the optical path construction of two-photon excitation and the application of saturated absorption spectrum frequency stabilization and superstabilility cavity frequency locking techniques are introduced in detail.The power-frequency electric field being modulated in RF field are measured by signal generator,mixer,parallel electrode plate and photodetector.The fourth chapter describes the main experimental process and results,and analyzes the experimental results and theories.By comparing the EIT spectra of Rydberg atoms without external field action and under RF field action,the relation between the frequency shift of AC-Stark of Rydberg EIT and the intensity of RF field is obtained.Finally,the amplitude of the RF electric field is modulated by the power-frequency electric field,and the amplitude and frequency of the power-frequency electric field are measured.The innovation of this paper:By taking advantage of the sensitivity of Rydberg atom to the external field and based on the AC-Stark effect of Rydberg atom,the electric field amplitude of power-frequency is accurately measured by measuring the frequency shift of EIT spectrum.Simultaneous measurement of frequency movement of different hyperfine energy levels can realize mutual calibration of multiple measurement results,thus improving the measurement accuracy of electric field amplitude of the measured working frequency.By measuring the variation of the peak value of the hyperfine spectrum with time,the precise measurement of the electric field frequency can be obtained by using trigonometric function fitting.The design scheme of experimental optical path and reference optical path is adopted,which greatly reduces the influence of external interference on the experiment and the influence caused by the laser itself.In addition,the differential detection of experimental optical path improves the signal-to-noise ratio and further improves the accuracy of the experiment.