  Amplitude-modulated nonlinear magneto-optical rotation is a powerful
technique that offers a possibility of controllable generation of given quantum
states. In this paper, we demonstrate creation and detection of specific
ground-state magnetic-sublevel superpositions in $^{87}$Rb. By appropriate
tuning of the modulation frequency and magnetic-field induction the efficiency
of a given coherence generation is controlled. The processes are analyzed
versus different experimental parameters.S
