Investigation of single-electron dynamics in tunnelling between zero- and one-dimensional states

We present an experimental technique for investigating the dynamics of single-electron tunnelling on a sub-nanosecond timescale without using fast gate pulses. We use surface acoustic waves (SAWs) to form dynamic quantum dots in a depleted one-dimensional channel. Each dynamic dot carries a single electron at SAW velocity ∼2800m/s. These dynamic dots are coupled to an open channel through a tunnel barrier for a length of ∼1μm. This allows each electron to tunnel out for a duration of ∼350ps. This fixed tunnel duration allows us to examine the dynamic nature of electron tunnelling without the need for gate pulses. Oscillations with ∼1% visibility are observed in the tunnel current as a function of gate voltage. We argue that these oscillations cannot be explained in the adiabatic limit, and that dynamic processes must be considered.