A MAGNETIC-RESONANCE STUDY OF NONADIABATIC EVOLUTION OF SPIN QUANTUM STATES

We use a nuclear-spin gyroscope for demonstrating non-adiabatic rotati onal effects and the geometric phase of a polarized Xe nuclear-spin en semble. We treat a spin-1/2 model system in a rotating magnetic field (with its inherent single-valued eigenstates) and a spin-3/2 system in a rotating electric field gradient (with a partially degenerate eigen state structure) including (i) spin polarization by polarization trans fer from optically pumped alkali atoms, (ii) spin-coherence excitation , and (iii) detection. The results are compared to those obtained by t he concept of geometric phases, where Berry's phase emerges as the adi abatic limit. Experimental results from gasphase nuclear magnetic reso nance of Xe-129 (I = 1/2) and Xe-131 (I = 3/2) are in excellent agreem ent with theoretical predictions.