Figure 3: (a) Effect of a short comoving pulse on the final velocities. The conditions are the same as in Figure 1(a) except the pulse duration, (instead of 4 ms), indicated (converted in value) by the broken vertical line. It is seen that the final velocity for atoms in state (upper green trajectory) is larger than for atoms in state (lower red trajectory). The two related wave packets fligh apart from each other, cancelling the interference effect between them once they are remixed (see text). (b) Compensation of this effect by means of a second reversed comoving pulse. The first pulse is the same as in 3(a) (starting time , duration , ). The second pulse starts at (second vertical broken line), its duration is also 1.5 ms and its amplitude is . Resulting trajectories are shown as in (a). Final velocities become equal to the initial velocity.