Yuting Sun

Fabrication of airbridges with gradient exposure

  1. Yuting Sun,
  2. Jiayu Ding,
  3. Xiaoyu Xia,
  4. Xiaohan Wang,
  5. Jianwen Xu,
  6. Shuqing Song,
  7. Dong Lan,
  8. Jie Zhao,
  9. and Yang Yu
In superconducting quantum circuits, airbridges are critical for eliminating parasitic slotline modes of coplanar waveguide circuits and reducing crosstalks between direct current magnetic
flux biases. Here, we present a technique for fabricating superconducting airbridges. With this technique, a single layer of photoresist is employed, and the gradient exposure process is used to define the profile of airbridges. In order to properly obtain the bridge profile, we design exposure dosage based on residual photoresist thickness and laser power calibrations. Compared with other airbridge fabrication techniques, the gradient exposure fabrication technique provides the ability to produce lossless superconducting airbridges with flexible size and, thus, is more suitable for large-scale superconducting quantum circuits. Furthermore, this method reduces the complexity of the fabrication process and provides a high fabrication yield.
arxiv pdf

Broadband merged-element Josephson parametric amplifier

  1. Yuting Sun,
  2. Xianke Li,
  3. Qingyu Wang,
  4. Tairong Bai,
  5. Xudong Liao,
  6. Dong Lan,
  7. Jie Zhao,
  8. and Yang Yu
Broadband quantum-limited amplifiers are essential for quantum information processing, yet challenges in design and fabrication continue to hinder their widespread applications. Here,
we introduce the broadband merged-element Josephson parametric amplifier in which the discrete parallel capacitor is directly integrated with the Josephson junctions. This merged-element design eliminates the shortcomings of discrete capacitors, simplifying the fabrication process, reducing the need for high-precision lithography tools, and ensuring compatibility with standard superconducting qubit fabrication procedures. Experimental results demonstrate a gain of 15 dB over a 500 MHz bandwidth, a mean saturation power of -116 dBm and near-quantum-limited noise performance. This robust readily implemented parametric amplifier holds significant promise for broader applications in superconducting quantum information and the advancement of quantum computation.
arxiv pdf