Measurements of cesium PJ-series quantum defect with the microwave spectroscopy

High-precision microwave spectroscopy has been used to measure the transition frequency of nS_1/2 → nP_J (n is the principle quantum number) and further the quantum defect of nP_J states in a standard cesium magneto-optical trap. A microwave field with 30-μs duration coupling the nS_1/2 → nP_1/2,3/2 transition yields a narrow linewidth microwave spectroscopy with the linewidth approaching the Fourier limit. After carefully compensating the stray electric and magnetic field and using the diluted atomic gas, we extract improved quantum defects of nP_J state, δ₀(nP_1/2) = 3.59159091(19), δ₂(nP_1/2) = 0.36092(35) and δ₀(nP_3/2) = 3.55907153(25), δ₂(nP_3/2) = 0.37344(47).