论文标题
超导量子相干电路损耗的定位和减少
Localization and reduction of superconducting quantum coherent circuit losses
论文作者
论文摘要
可以通过超导微波电路实现量子传感和计算。 Qubits是具有非线性Josephson连接的电容器和电感器的工程量子系统。它们在单兴就的量子状态下运行，在6.5 GHz的$27μ$ EV的光子中运行。量子相干性从根本上受到材料缺陷的限制，特别是在电路界面的无定形介电中的原子尺度寄生两级系统（TLS）。[1]驱动量子电路中振荡电荷的电场会引起人们共鸣，并产生相位噪声和耗散。我们使用二利机上的共团niobium on-silicon超导谐振器来探测量子电路的脱碳。通过选择性修改界面电介质，我们表明大多数TLS损耗来自硅表面氧化物，并且大多数非TLS损耗分布在整个尼伯特表面氧化物中。通过工具后的接口修改，我们将TLS损失降低了85％，非TLS损失减少了72％，获得了创纪录的单光子谐振质量因子，并接近了非TLS损失占主导地位的政权。 [1]Müller，C。，Cole，J。H.＆Lisenfeld，J。致力于理解无定形固体中的两级系统：量子电路的见解。众议员物理。 82，124501（2019）
Quantum sensing and computation can be realized with superconducting microwave circuits. Qubits are engineered quantum systems of capacitors and inductors with non-linear Josephson junctions. They operate in the single-excitation quantum regime, photons of $27 μ$eV at 6.5 GHz. Quantum coherence is fundamentally limited by materials defects, in particular atomic-scale parasitic two-level systems (TLS) in amorphous dielectrics at circuit interfaces.[1] The electric fields driving oscillating charges in quantum circuits resonantly couple to TLS, producing phase noise and dissipation. We use coplanar niobium-on-silicon superconducting resonators to probe decoherence in quantum circuits. By selectively modifying interface dielectrics, we show that most TLS losses come from the silicon surface oxide, and most non-TLS losses are distributed throughout the niobium surface oxide. Through post-fabrication interface modification we reduced TLS losses by 85% and non-TLS losses by 72%, obtaining record single-photon resonator quality factors above 5 million and approaching a regime where non-TLS losses are dominant. [1]Müller, C., Cole, J. H. & Lisenfeld, J. Towards understanding two-level-systems in amorphous solids: insights from quantum circuits. Rep. Prog. Phys. 82, 124501 (2019)
