Direct control of the tunnel splitting in a one-electron double quantum dot

Quasistatic transport measurements are employed on a laterally defined tunnel-coupled double quantum dot. A nearby quantum point contact allows us to track the charge as added to the device. If charged with only up to one electron, the low-energy spectrum of the double quantum dot is characterized by its quantum mechanical interdot tunnel splitting. We directly measure its magnitude by utilizing particular anticrossing features in the stability diagram at finite source-drain bias. By modification of gate voltages defining the confinement potential, as well as by variation of a perpendicular magnetic field, we demonstrate the tunability of the coherent tunnel coupling.