Semiconductor quantum dots in which electrons or holes are isolated via electrostatic potentials generated by surface gates are promising building blocks for semiconductor-based quantum technology. Here, we investigate double-quantum-dot (DQD) charge qubits in GaAs capacitively coupled to high-impedance superconducting quantum interference device array and Josephson-junction array resonators. We tune the strength of the electric-dipole interaction between the qubit and the resonator in situ using surface gates. We characterize the qubit-resonator coupling strength, the qubit decoherence, and the detuning noise affecting the charge qubit for different electrostatic DQD configurations. We find all quantities to be systematically tunable over more than one order of magnitude, resulting in reproducible decoherence rates ${\mathrm{\Gamma }}_2/2\pi <5\mathrm{MHz}$ in the limit of high interdot capacitance. In the opposite limit, by reducing the interdot capacitance, we increase the DQD electric-dipole strength and, therefore, its coupling to the resonator. Employing a Josephson-junction array resonator with an impedance of approximately $4\mathrm{k}\mathrm{\Omega }$ and a resonance frequency of ${\omega }_r/2\pi \sim 5.6\mathrm{GHz}$, we observe a coupling strength of $g/2\pi \sim 630\mathrm{MHz}$, demonstrating the possibility to operate electrons hosted in a semiconductor DQD in the ultrastrong-coupling regime (USC). The presented results are essential for further increasing the coherence of quantum-dot-based qubits and investigating USC physics in semiconducting QDs.

中文翻译：

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双点电荷量子比特的电偶极子强度的原位调谐：电荷噪声保护和超强耦合

其中电子或空穴通过表面栅极产生的静电势隔离的半导体量子点是基于半导体的量子技术的有希望的构建模块。在这里，我们研究了电容耦合到高阻抗超导量子干涉器件阵列和约瑟夫森结阵列谐振器的 GaAs 中的双量子点 (DQD) 电荷量子位。我们在原位调整量子比特和谐振器之间的电偶极子相互作用的强度使用表面浇口。我们描述了影响不同静电 DQD 配置的电荷量子比特的量子比特-谐振器耦合强度、量子比特退相干和失谐噪声。我们发现所有量都可以系统地调整超过一个数量级，从而产生可重现的退相干率${\mathrm{\Gamma }}_2/2\pi <5\mathrm{兆赫}$在高点间电容的限制。在相反的限制下，通过减少点间电容，我们增加了 DQD 电偶极子强度，因此增加了它与谐振器的耦合。采用约瑟夫森结阵列谐振器，其阻抗约为$4\mathrm{ķ}\mathrm{\Omega }$和共振频率${\omega }_r/2\pi ～5.6\mathrm{千兆赫}$，我们观察到耦合强度为$G/2\pi ～630\mathrm{兆赫}$，展示了在超强耦合机制（USC）中操作半导体DQD中电子的可能性。所呈现的结果对于进一步提高基于量子点的量子比特的相干性和研究半导体量子点中的 USC 物理学至关重要。