Sublevel echoes induced by resonant light pulses: Quantum beat echoes

Abstract

We predict and observe a new class of echoes of atomic sublevel coherences induced by two impact excitations with resonant light pulses which may be either coherent or incoherent. The Zeeman-sublevel echoes in 3 2S 1 2 of sodium were observed by using polarization selective detection technique under the excitation condition that the optical T 2 (5 × 10 -11 s) was much shorter than the pulse width (5 ns). Theoretical analysis also predicts the echoes involving coherence transfer between ground and excited states.