The spectrum of the spin particle in oscillatory potential subjected to external parabolic magnetic field B=(B0+Gx+G~x2)z^ is obtained. The structure of energy levels of the considered system allows to identify the frequency of the oscillator via the spectrum of spin sublevels coming only from {\it one} oscillatory level. The effect is due to the gradient terms in the form of the field.
@article{arxiv.quant-ph/9908053,
title = {MR spectroscopy with parabolic magnetic field: spin-oscillator coupling effect},
author = {Czeslaw Lewa and Pawel Horodecki and Ryszard Horodecki and Michal Horodecki},
journal= {arXiv preprint arXiv:quant-ph/9908053},
year = {2007}
}