Nv. Vitanov, Pulse-order invariance of the initial-state population in multistate chains driven by delayed laser pulses, PHYS REV A, 60(4), 1999, pp. 3308-3310
This paper shows that under certain symmetry conditions the probability of
remaining in the initial stale (the probability of no transition) in a chai
nwise-connected multistate system driven by two or more delayed laser pulse
s does not depend on the pulse order. [S1050-2947(99)01010-0].