Suppression of Leakage for a Charge Qubit in Triangular Triple Quantum Dots

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.