Fig. 3: Isolated 2 × 2, 4-electron array.
From: Combining multiplexed gate-based readout and isolated CMOS quantum dot arrays
a SEM micrograph of the central 2 × 2 array. b Illustration of vertical (top) and horizontal (bottom) detunings using virtual gates \({{{{{\rm{T}}}}}}_{1}^{{\prime} }\), \({{{{{\rm{T}}}}}}_{2}^{{\prime} }\), \({{{{{\rm{B}}}}}}_{1}^{{\prime} }\) and \({{{{{\rm{B}}}}}}_{2}^{{\prime} }\). c Stability diagram at large positive horizontal detuning where 4 electrons are distributed in the left column. d Stability diagram of the 2 × 2 array in the large tunnel coupling regime using vertical and horizontal detuning. The signal is the combination of resonator 1 and 2. Each bare signal is digitized using a threshold with a color pixel for points with signal above the threshold (red for resonator 1 and blue for resonator 2) and a white pixel for points below. To find the \(\left(\begin{array}{cc}1&1\\ 1&1\end{array}\right)\) charge configuration we start with all electrons in T1 (large positive ϵX and large negative ϵY). We play then with ϵX to transfer two charges in T2 and reach \(\left(\begin{array}{cc}2&2\\ 0&0\end{array}\right)\). ϵY is then swept toward zero detuning to transfer one electron from each top quantum dot to each bottom quantum dot.
