摘要：state) for the one-photon transition and 1.8 ns (corresponding to the Doppler width of the warm atomic vapor) for the two-photon transition. We confirmed that the coherence time of the SPs can vary in accordance with the photons emitted from the one- or two-photon transitions in the ladder-type atomic system. The correlated SPs obtained via the two-photon transition contributed to almost all the velocity classes of the atoms in the Doppler-broadened atomic ensemble.
