Transmission spectra of the cavity that show the vacuum Rabi splitting. The black dots (red dots) are the experimental data for empty cavity (atoms in cavity mode) and the green (blue) curve is the theoretical fitting. The cavity decay rate is κ = 2 π × ( 6.6 ± 0.2 ) MHz . There are approximately 100 (±2) atoms transported inside the cavity with a Rabi splitting of 94 MHz. The asymmetry of splitting peaks attributes to a red detuning (−16 ±0.8 MHz) between cavity and atoms caused by ODT. Each point of the data is an average over 15 complete measurements obtained within 150 μ s .