We present a theoretical proposal of a tunable charge qubit, hosted in triple quantum dots. The manipulation is solely performed by changing the heights of the two potential barriers between the three dots, while the energy of all three dots are fixed. We have found that when the relative height of the two barriers are changed, the direction of the axis of rotation in performing single-qubit gates can be varied. On the other hand, the corresponding rotation speed can be tuned by raising or lowering the two barriers at the same time. Our proposal therefore allows for tunability of both the rotation axis and rotating speed for a charge qubit via all-electrical control, which may facilitate realization of quantum algorithms in these devices. arXiv:1805.04221v2 [cond-mat.mes-hall]

This paper presents a simple yet effective strategy to suppress the leakage in a three‐quantum‐dot charge qubit system by having the dots in a triangle as opposed to the linear geometry commonly conceived. It is found that the tunnel coupling between the two outmost dots is amplified in triangular triple dots, which consequently reduces leakage by separating the leaked state and qubit states. It has been found that the leakage can be suppressed by as much as five orders of magnitude when the dots form an equilateral triangle, with further improvement of control fidelities possible if composite pulses are applied.

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