Absolute measurement of microwave power based on the atomic rabi frequency

The purpose of this study is to develop a new microwave power standard. In this study we demonstrate the measurement of the absolute power of a microwave at a frequency of approximately 9.2 GHz using the Rabi frequency of cesium atoms in a glass cell inserted into a WR90 waveguide. The Rabi frequency was converted into the microwave field strength. Then the absolute power was estimated by analyzing the distribution of the microwave field and the impedance mismatch in the waveguide containing the glass cell. The relative measurement uncertainty was typically less than 5%.