The Engineering Salon aims at communication, break- through, succession, innovation and development, which will provide a platform for exchange and demonstration, and encourage the engineer craftsman spirit of overcoming difficulties and striving for perfection in the engineering team.  All scientists, postdocs and engineers are welcome to join us!

Date: Jul 22, 2021 (Thursday) 13:30-15:40

Venue: Room 526

Host: Tiefu Li, Director of Division of Quantum Engineering Research

1) Measurement of superconducting qubits and optimization of readout fidelity without JPA.

Keywords: Superconducting Quantum Chip Preparation，Wire Bonding, Measurement of Superconducting Qubit

Zhen Yang,  Engineer

Abstract: The superconducting qubit will inevitably be affected by unnecessary noise    during the control process，as well as inappropriate parameters of the chip itself, will increase the difficulty for us to distinguish between |0> and |1> and reduce the fidelity of the gate, which greatly restricts our experiments. This report will introduce how to use a combination of carefully designed microwave pulses and high precision time controlled magnetic fields to control and read qubits at low power, and optimize system parameters to achieve a Singleshot readout fidelity of more than 90% without JPA.

2) The Introduction of dilution refrigerator and the measurement of the sample temperature

Keywords: Maintenance of dilution refrigerator, Measurement under low temperature and strong magnetic field, Mechanical drawing, ARPES.

Ya Feng, Senior Engineer

Abstract: Temperature is one of the most basic physical quantities, and it is also an important parameter to control the quantum state of matter. The lower the temperature is, the easier it is to discover and study abundant quantum phenomena. In this report, I will briefly introduce the dilution refrigerator, which is widely used in scientific research to obtain cryogenic environment, including its principle and basic components. Finally, the design and manufacture of cell and the measurement of sample temperature are introduced.

3) The introduction of the technology of contact-proximity lithography 

Keywords: Micro-Electronic-Mechnical System（MEMS）, Design and construction of cleanroom

Jiangang Zhang, Senior Engineer

Abstract: Contact-proximity lithography is a kind of classical technology. Due to the practicality on cost and short time span, contact-proximity lithography still have a broad application on micro-nano scale fabrication. In this report based on the principle of contact-proximity lithography, some key elements of this technology will be analyzed, such as: choosing the mode of exposure, the leveling between mask and wafer, the back side alignment, the marker of mask, the influence of substrate on the exposure.

4) Optimization of qubit-phonon device fabrication techniques

Keywords: Lithography, Etching, Flip-chip bonding, Packaging

Tang Su, Senior Engineer

Abstract: Superconducting quantum computing represents the quantum computing solution based on superconducting circuits. Due to its rapid development in recent years, superconducting quantum computing has become quite competitive among candidates for realizing universal quantum computers. On the other hand, hybrid systems, e.g., superconducting qubit coupled with acoustic waves, have shown potential for applications in quantum-limited transducers, quantum buses/memories, etc. In this talk I will briefly introduce our recent works in quantum acoustic project, including device fabrication and some preliminary data, as well as perspectives of future works.

5) Preparation and characterization of NbTiN nano-film

Keywords: Coating, Etching, Nano-film growth, Fabrication of superconducting resonator

Yuqing Wang, Engineer

Abstract: In recent years, with the more and more attention of quantum computing, the fabrication of superconducting coplanar waveguide resonator has been paid lots of attention, and its applications in single photon detection, molecular magnet detection, narrow-band filtering and quantum parametric amplifier are gradually increasing. Therefore, it is significant to fabricate high-quality superconducting coplanar waveguide resonator. We choose NbTiN nano-film which has wide band gap, good conductivity, and more importantly, it can work in a certain parallel magnetic field, to make the resonant cavity.