Spin decoherence of an orbitally-excited electron in a moving quantum dot

It has been demonstrated experimentally that surface acoustic waves (SAW), via piezoelectric interaction, can move electrons between distant quantum dots. Due to the high speed of the SAW generated moving dot, the pick-up process where an electron is transferred from a fixed quantum dot to a moving quantum dot could be highly non-adiabatic, and the electron being transported would enter a superposition of many highly excited orbital states. In this work we explore the spin dynamics of an electron in highly excited orbital states in a moving quantum dot in GaAs, and investigate both spin relaxation through electron-phonon interaction and spin dephasing caused by effective g-factor variations in highly excited orbital states. We show that while corrections to both spin relaxation and spin dephasing have quite strong dependence on orbital excitation, the magnitudes of these corrections are relatively small: spin relaxation is suppressed by the phonon bottleneck effect, and the g-factor correction is in the order of 0.01% using experimentally relevant parameters. Therefore, for intermediate distance transport, orbital excitation should not lead to significant spin decoherence for the transported electron.