We experimentally demonstrated the coherent trapping of light with orbital angular momentum as a stationary light pulse in a cold 87 Rb atomic medium by measuring a fork pattern interference.
We report on the generation of light carrying orbital angular momentum through Bragg diffraction into an electromagnetically induced coherence grating in a degenerate two-level system of cold cesium atoms, demonstrating the c onservation the c onservation of orbital angular momentum of light in a coherent four-wave mixing process. The induced Zeeman coherence grating is shown to contain the spatial phase structure of the incident beams. The e xchange of phase information between a light beam with orbital angular momentum and a long-lived atomic coherence opens up the way to process quantum process information encoded in a multidimensional state space.