2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89136We present the first scheme for producing and measuring an Abelian geometric phase shift in a three-level system where states are invariant under a non-Abelian group. In contrast to existing experiments and proposals for experiments, based on U(1)-invariant states, our scheme geodesically evolves U(2)-invariant states in a four-dimensional SU(3)/U(2) space and is physically realized via a three-channel optical interferometer.4 pages, 3 figuresQuantum Physicstext