Spin-orbit engineering of semiconductor heterostructures: A spin-sensitive quantum-phase shifter

In noncentrosymmetric semiconductors with zinc-blende structure grown along the [110] crystallographic direction, electrons with up- and down-spins undergo different quantum-phase shifts upon tunneling, which can be viewed as resulting from spin precession around a complex magnetic field. There is no spin filtering but a pure spin dephasing. The phase shift of the transmitted wave is proportional to the overall barrier-material thickness. We show that a device incorporating a number of resonant tunnel barriers constitutes an efficient quantum-phase shifter.