Coherent manipulation of charge qubits in double quantum dots

TL;DR

This paper theoretically investigates the coherent charge transfer in double quantum dots driven by fast bias-voltage switches, revealing how oscillations depend on system parameters and confirming the coherent nature of electron transfer.

Contribution

It provides a combined numerical and analytical study of charge qubit manipulation, clarifying the dependence of oscillations on level offset and initialization, advancing understanding of quantum dot control.

Findings

Oscillations depend on level offset during manipulation.

Initialization stage influences electron transfer oscillations.

Analytical model explains key features of the observed oscillations.

Abstract

The coherent time evolution of electrons in double quantum dots induced by fast bias-voltage switches is studied theoretically. As it was shown experimentally, such driven double quantum dots are potential devices for controlled manipulation of charge qubits. By numerically solving a quantum master equation we obtain the energy- and time-resolved electron transfer through the device which resembles the measured data. The observed oscillations are found to depend on the level offset of the two dots during the manipulation and, most surprisingly, also the on initialization stage. By means of an analytical expression, obtained from a large-bias model, we can understand the prominent features of these oscillations seen in both the experimental data and the numerical results. These findings strengthen the common interpretation in terms of a coherent transfer of electrons between the dots.