DEVIATION FROM BERRY ADIABATIC GEOMETRIC PHASE IN A XE-131 NUCLEAR GYROSCOPE

The concept of geometric phase is demonstrated in a nuclear gyroscope using Xe-131 nuclear spins (I = 3/2) as sensors for quantum-phase accumulation. By spatial rotation sub-Hertz splittings due to geometric phases are resolved in nuclear-quadrupole spectra. Deviations from Berry's adiabatic geometric phase appear in the regime of nonadiabatic rotation. The observed frequency splittings are no longer linear in the rotational frequency, as expected from adiabatic rotations, and all possible transitions, namely, six in this partially degenerate spin-3/2 system, are observed experimentally.