Magnetic grating echo from room temperature Rb atoms

We have initiated a new class of coherent transient experiments with Doppler-broadened atoms confined in a vapor cell. A spatially modulated coherence is created between magnetic sublevels of the F=3 ground state of /sup 85/Rb by a "standing wave" pulse. This pulse consists of two opposite circularly polarized traveling waves with wave vectors K/sub 1/ and K/sub 2/ at a small angle /spl theta/. The coherence grating is probed by the application of a "readout" pulse along K/sub 2/. The resulting coherent emission along K/sub 1/ is detected by a heterodyne technique.