Time-irreversible random telegraph signal due to current along a single hopping chain

We have directly observed individual hopping events in the flow of curent along a single chain of localized states. These events modulate the conductance of a ballistic constriction formed in GaAs/Alₓ{Ga}_{1{{-}}x}$As split-gate transistor, resulting in a time irreversible random telegraph signal. The hopping chain, carrying approximately one electron per second, is situated between the gate and the two-dimensional electron gas, and can be altered by varying the gate voltage.