Time sequence of an experimental circle. ε_± denotes the time sequence of signal light, which shows that the signal pulse is stored at the j-th storage trial. C, P, and B₀ denote the time sequences of the controlling light, pumping light, and guiding magnetic field, respectively. τ_M is the MOT-on time interval; τ_d = 10 μs is the waiting time for MOT magnetic field decaying to zero. τ_P = 5 μs is the atomic preparation time in the first trial. T_P = 100 ns is the time window of the atomic preparation in the j-th (j > 1) trial. T_W = T_R = 100 ns and T_S = 200 ns are the writing, reading, and waiting windows, respectively.