document: A 3D finite element based (FEM) COMSOL capacitance analysis is combined with Monte Carlo single-electron circuit simulations to model device operations during single electron detection. The 3D structural data (Fig. 1b) of the nanoscale DQD pair and multiple gate electrodes are precisely input into COMSOL’s FEM-based electrostatics simulator. Capacitances between different device components are then extracted and fed into the well-tested single electron circuit simulator SETSPICE [11], based on the orthodox theory of single electron tunnelling [12]. For our target d1 of 60nm, simulation results (Fig. 1c) showed that as we sweep the voltage applied on gate G1, VG1, single electron tunnelling into the turnstile’s two QDs should generate shifts in the electrometer current, IDS, of tens of pA. This is well within the charge sensitivity of DQD electrometer [6] and consistent to the same order of magnitude with previous work in single electron detection [13]. In addition, the gate to QD capacitive coupling appear to be sufficient for the control of QD occupations down to the single electron limit, allowing for future manipulation of single electron spins in qubit research.
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