  We demonstrate manipulation of quantum interference by controlling the
competitions between weak localization (WL) and weak antilocalization (WAL) via
variation of the gate voltages of double- gate amorphous InGaZnO thin-film
transistors. Our study unveils the full profile of an intriguing universal
dependence of the respective WL and WAL contributions on the channel
conductivity. This universality is discovered to be robust against interface
disorder.
