  In this letter, we show that a superconducting two-dimensional electron gas
is formed at the LaTiO3/SrTiO3 interface whose transition temperature can be
modulated by a back-gate voltage. The gas consists of two types of carriers : a
majority of low-mobility carriers always present, and a few high-mobility ones
that can be injected by electrostatic doping. The calculation of the electrons
spatial distribution in the confinement potential shows that the high-mobility
electrons responsible for superconductivity set at the edge of the gas whose
extension can be tuned by field effect.
