Manipulation and transport of spin coherence in semiconductors

Summary form only given. Coherent spin information can flow across interfaces of dissimilar materials in engineered structures. The interfaces appear surprisingly permeable over a broad range of temperatures, and the transport of spin information can be controlled with both electric and magnetic fields. Even in materials where momentum scattering is strongly enhanced by defects, spin coherence persists to room temperature. In order to manipulate these states, we have developed additional techniques with the potential for coherent all-optical control over electron spins in nanostructures on femtosecond time scales. Spin splittings corresponding to effective magnetic field strengths of 20 T have been produced using circularly-polarized, below-bandgap pulses with the optical Stark effect. Changes in the magnetization of resonantly tipped nuclei demonstrate the ability to perform all-optical nuclear magnetic resonance (NMR). This sensitive and spatially selective NMR technique may serve as a basis for the coherent manipulation of nuclear moments at the atomic level.