Figure 1: Schematic depiction of spin-orbit fields as a function of electron crystal momentum in a zincblende quantum well grown along each of three special directions: (a) $[001]$, (b) $[110]$, (c) $[111]$. The spin-orbit field from the quantum well symmetry is indicated in blue, and the electric-field-induced spin-orbit field is indicated in red. For (c) the two fields have the same momentum-dependent structure.