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

We use a nuclear-spin gyroscope for demonstrating non-adiabatic rotational effects and the geometric phase of a polarized Xe nuclear-spin ensemble. 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 eigenstate structure) including (i) spin polarization by polarization transfer from optically pumped alkali atoms, (ii) spin-coherence excitation, and (iii) detection. The results are compared to those obtained by the concept of geometric phases, where Berry's phase emerges as the adiabatic limit. Experimental results from gasphase nuclear magnetic resonance of Xe-129 (I = 1/2) and Xe-131 (I = 3/2) are in excellent agreement with theoretical predictions.