A study of adiabaticity in electron transport by surface acoustic wave

Surface acoustic waves have been suggested as a carrier to enable remote transport of a single or multiple electrons from one quantum dot to another while maintaining quantum information encoded in the electron’s spin or orbital degrees of freedom. It is widely believed that the process where SAW picks up the electron from a fixed quantum dot is adiabatic, with the electron wavefunction following the instantaneous ground state centered at the collective potential minimum. In this work we explore the adiabaticity of this electron transfer from a static to a moving (or vice versa) dot as we vary system parameters such as relative dot sizes, bias potential, and speed of the moving dot. In particular, we show that in a wide range of parameters, during the SAW pick-up process the electron could end up in a superposition state that includes many highly excited orbital states, gaining energy from the SAW potential.

The high degree of excitation could negatively affect the electron spin decoherence, causing loss of quantum information encoded in the spin.