Acoustoelectric current transport through a double quantum dot

We present acoustoelectric current measurements through a double quantum dot. Due to background impurity potential fluctuations an unintentional quantum dot is situated next to an intentionally induced single dot. By changing the top gate voltages, each of the two dots alone can be addressed separately but also a situation can be realized where both dots are coupled and form a double quantum dot system. In the regime that is dominated by the conduction through the intentional quantum dot quantized charge transport has been realized mediated by surface acoustic waves. Based on the measurements on this device we propose a mechanism for a parallel double quantum dot turnstile that can be used as a spin entangler.

Figure 1

Schematic sketch of the measurement setup with an electron microscope picture of the central region of the split gates.

Figure 2

Gray scale plot of the conductance for sweeping both outer split gates. The inset shows two single measurements at the dashed lines.

Figure 3

Repetition of the gray scale plot of Fig 2. The inset shows a schematic drawing of the device layout and the two quantum dots.

Figure 4

Two measurements along the dashed line (c) of Fig. 3 with and without a SAW applied. The inset shows a schematic drawing of the turnstile mechanism responsible for the current quantization.

Figure 5

Two measurements along the dashed line (d) of Fig. 3 with and without a SAW applied. The inset highlights the position of the anticrossing.

Figure 6

Schematic drawing of the double dot spin entangler