Abstract: Utilizing the advantages of low temperature of cold atoms, narrow spectral peaks of Rydberg Electromagnetic Induction Transparency (EIT), and clear atomic quantum states. The polarization of the microwave can be measured directly through spectral intervals in cold atomic samples based on Rydberg EIT and Autler-Townes (AT) splitting. The results show that the splitting interval of the Rydberg EIT-AT varies monotonously with the polarization of the microwave electric field and is proportional to the projection of the polarization of the microwave electric field on the polarization direction of the probe laser. The resolution is 3.2 °. Compared with the traditional method of using EIT resonance to detect the change of light transmittance in the hot atom vapor cell, the method based on cold atom EIT-AT splitting interval has the advantages of more direct, accurate and simple analysis. This work is of great significance to the absolute measurement of microwave polarization and the calibration of electric field strength.

Key words: Quantum sensing, Microwave field, Rydberg atom, Electromagnetic induction transparency