Electrical spin protection and manipulation via gate-locked spin-orbit fields

摘要

The spin-orbit (SO) interaction couples electron spin and momentum via arelativistic, effective magnetic field. While conveniently facilitatingcoherent spin manipulation in semiconductors, the SO interaction alsoinherently causes spin relaxation. A unique situation arises when the Rashbaand Dresselhaus SO fields are matched, strongly protecting spins fromrelaxation, as recently demonstrated. Quantum computation and spintronicsdevices such as the paradigmatic spin transistor could vastly benefit if suchspin protection could be expanded from a single point into a broad rangeaccessible with in-situ gate-control, making possible tunable SO rotationsunder protection from relaxation. Here, we demonstrate broad, independentcontrol of all relevant SO fields in GaAs quantum wells, allowing us to tunethe Rashba and Dresselhaus SO fields while keeping both locked to each otherusing gate voltages. Thus, we can electrically control and simultaneouslyprotect the spin. Our experiments employ quantum interference corrections toelectrical conductivity as a sensitive probe of SO coupling. Finally, wecombine transport data with numerical SO simulations to precisely quantify allSO terms.