Fig. 1. Experimental system. (a) Schematic of experimental setup; (b) schematic of MW-RF two-photon transition between rubidium 87 atomic ground states; (c) atomic levels involved with pump and probe fields; (d) experimental sequence diagram; (e) PD signal. The probe laser is switched on at t'=0 immediately after the MW-RF pulse and the PD signal rises from V0 and approaches to a stable value V1 at t'=5 ms

Fig. 2. Thermal relaxation and microwave frequency scanning. (a) Atomic population of F=2 during thermal relaxation; (b) resonance peaks corresponding to the microwave transitions of |1,0>?|2,-1>,|1,-1>?|2,0>(left) and |1,0>?|2,0> (right) separated by 2.278 MHz

Fig. 3. MW-RF two-photon Rabi oscillation. (a) Atomic population of F=2 state when the MW-RF pulse is switched on (dots) and off (squares) with Δ=60 kHz, δ=500 Hz; (b) Rabi oscillation of MW-RF two photon transition by removing the thermal relaxation background; (c) dependence of generalized Rabi frequency on two-photon detuning. The parameters PMW=8 W, PRF=2 W and Δ=60 kHz are fixed

Fig. 4. Dependence of Rabi frequency on intermediate state detuning, MW and RF powers. (a) Two-photon Rabi frequency Ω' versus intermediate state detuning Δ; (b) two-photon Rabi frequency versus the power of microwave; (c) two-photon Rabi frequency versus the power of radio frequency