Observation of quantum level spectrum for silicon double single-electron transistors

Double quantum dots (DQDs) have been studied as attractive candidates for charge qubits. Initially, GaAs-based DQDs formed by means of surface gates depletion were studied because many parameters are tunable after their fabrications [1]. However, silicon-based DQDs are more promising for charge qubits because of the absence ofpiezoelectric electron-phonon coupling, and the effect of phonon localization [2]. Furthermore, to integrate Si multiple charge qubits and a readout device in a small footprint, a series-connected double dots transistor has recently been proposed and studied [3]. The readout is called as double single-electron transistors (DSETs) and facilitates to detect the single-charge polarizations on the adjacent double qubits efficiently [4]. The other advantage of DSETs is that both two SETs act as feedback transistors to each other to compensate the random fluctuation noise.