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

TL;DR

This paper proposes a hybrid system of triple-quantum-dot charge qubits coupled via a superconducting resonator, enabling high-fidelity entangling gates in both dispersive and resonant regimes, advancing semiconductor quantum computing.

Contribution

It introduces a new charge qubit design and demonstrates two high-fidelity entangling gates using a hybrid qubit-resonator system in different operational regimes.

Findings

iSWAP gate fidelity exceeds 99% under typical noise conditions

Holonomic gate fidelity surpasses 98% with sufficient resonator anharmonicity

The system enables long-range coupling and high-fidelity gates for semiconductor charge qubits

Abstract

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 new 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 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 semiconductor quantum dot.