论文标题
改善了超导量子电路的约瑟夫森连接点可重复性：阴影蒸发和氧化
Improving Josephson junction reproducibility for superconducting quantum circuits: shadow evaporation and oxidation
论文作者
论文摘要
用于量子电路的超导Qubit的最常用的物理实现是一种跨度。有许多超导量子电路应用，芯片上的约瑟夫森连接临界电流可重复性至关重要。在这里，由于对阴影蒸发和氧化步骤的全面研究，我们报告了强大的芯片量表$ al/alo_x/al $交界器制造方法。我们在实验上证明了最佳的约瑟夫森连接电极厚度，沉积速率和沉积角的证据，从而确保最小的电极表面和线边缘粗糙度。确定氧化方法，压力和时间对临界电流可重复性的影响。通过提出的方法，我们证明了$ al/alo_x/al $连接制造，其关键电流变化（$σ/i_c $）少于3.9％（从$ 150 \ $ 150 \ times200 $到$ 150 \ $ 150 \ times600 $ $ nm^2 $ afor）和7.7％（$ 100 \ times100 \ times100 $ $ nm^2 $ $ nm^$ chip） + $ chip + $ chip^22020202020202020202020202020 $^$^$^$^$^tips 20 f。最后，我们分别制造三个$ 5 \ times10 $ $ mm^2 $芯片，带有18个Transmon Qubits（接近4.3 GHz频率），显示不同芯片上量子的频率变化小于1.9％。所提出的方法和优化标准可用于稳健的晶状尺度超导量子电路制造。
The most commonly used physical realization of superconducting qubits for quantum circuits is a transmon. There are a number of superconducting quantum circuits applications, where Josephson junction critical current reproducibility over a chip is crucial. Here, we report on a robust chip scale $Al/AlO_x/Al$ junctions fabrication method due to comprehensive study of shadow evaporation and oxidation steps. We experimentally demonstrate the evidence of optimal Josephson junction electrodes thickness, deposition rate and deposition angle, which ensure minimal electrode surface and line edge roughness. The influence of oxidation method, pressure and time on critical current reproducibility is determined. With the proposed method we demonstrate $Al/AlO_x/Al$ junction fabrication with the critical current variation ($σ/I_c$) less than 3.9% (from $150\times200$ to $150\times600$ $nm^2$ area) and 7.7% (for $100\times100$ $nm^2$ area) over $20\times20$ $mm^2$ chip. Finally, we fabricate separately three $5\times10$ $mm^2$ chips with 18 transmon qubits (near 4.3 GHz frequency) showing less than 1.9% frequency variation between qubit on different chips. The proposed approach and optimization criteria can be utilized for a robust wafer-scale superconducting qubit circuits fabrication.
