Coherence transfer in three-level systems: controlled violation of adiabaticity and antiparallel double resonant irradiation

It is shown by theory and expt. how coherent superpositions of quantum states in 3-level systems can be manipulated by irradiating 2 connected transitions with 2 resonant fields with suitably shaped time-dependent amplitudes and phases. Three variants are discussed; (i) adiabatic coherence transfer (ACT) between 2 transitions, which may be either allowed or forbidden; (ii) nonadiabatic transfer of coherence to a nonirradiated transition by controlled violation of adiabaticity (CVA); (iii) coherence transfer to a nonirradiated transition by antiparallel double resonant irradn. (APDRI). A geometrical representation of these expts. gives a clear phys. picture of the phenomena and provides a tool for the development of new methods. The principles are illustrated exptl. by applications to magnetic resonance of D (I = 1) in anisotropic phase at high magnetic field, but could also be applied to 3 level-systems in NQR, optics, and other areas of spectroscopy. [on SciFinder (R)]