  We introduce a method to suppress unwanted transition channels, even without
knowing their couplings, and achieve perfect population transfer in multistate
quantum systems by the application of composite pulse sequences. Unwanted
transition paths may be present due to imperfect light polarization, stray
electromagnetic fields, misalignment of quantization axis, spatial
inhomogeneity of trapping fields, off-resonant couplings, etc. Compensation of
simultaneous deviations in polarization, pulse area, and detuning is
demonstrated. The accuracy, the flexibility and the robustness of this
technique make it suitable for high-fidelity applications in quantum optics and
quantum information processing.
