Coupling two charge qubits via a superconducting resonator operating in the resonant and dispersive regimes

A key challenge for semiconductor quantum-dot charge qubits is the realization of long-range qubit coupling and performing high-fidelity gates based on it. Here, we describe a different type of charge qubit formed by an electron confined in a triple-quantum-dot system, enabling single and two-qubit gates working in the dipolar and quadrupolar detuning sweet spots. We further present the form for the long-range dipolar coupling between the charge qubit and the superconducting resonator. Based on the hybrid system composed of the qubits and the resonator, we present two types of entangling gates: the dynamical iSWAP gate and holonomic entangling gate, which are operating in the dispersive and resonant regimes, respectively. We find that the fidelity for the iSWAP gate can reach a fidelity higher than 99% for the noise level typical in experiments. Meanwhile, the fidelity for the holonomic gate can surpass 98% if the anharmonicity in the resonator is large enough. Our proposal offers an alternative, useful way to build up high-fidelity quantum computation for charge qubits in the semiconductor quantum dot.

Automated summary

A key challenge in semiconductor quantum-dot charge qubits is achieving long-range qubit coupling and performing high-fidelity gates. This study presents a different type of charge qubit formed by an electron confined in a triple-quantum-dot system, enabling single and two-qubit gates in specific detuning sweet spots. The study also proposes a form of long-range dipolar coupling between the charge qubit and superconducting resonator, allowing for entangling gates in both dispersive and resonant regimes.