Fig. 2. Various single-electron configurations within the array.

a–c Three different double-dot configurations, controlled by compensated voltages $V_{1,2,3}^{\mathrm{c}}$. Numbers indicate the occupation of the three qubit dots (each red dot represents one electron). d Similar to c, but with $V_2^{\mathrm{c}}$ fixed at a larger positive voltage, revealing the triple-dot ground-state region. In a–d the top gate is fixed at 6 V.