Towards optimising superconducting transmon qubits

• Main Author: Soe, Thant Gon Yee
• Other Authors: Rainer Helmut Dumke
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Science::Physics::Atomic physics::Quantum theory
• Online Access: https://hdl.handle.net/10356/157025
• Institution: Nanyang Technological University

Superconducting qubits are promising in the field of quantum computing therefore, optimising quantum hardware especially superconducting qubit chips will pave the way for greater progress. In this thesis, we focus on the fabrication and measurement of the 3D transmon qubits for single junction as well as SQUID junctions. One critical process is the fabrication of Josephson junction for the transmon qubit. Oxidation time for junction fabrication is examined. Resistances of the qubits are measured using program designed to complement the instrument and replace the pre-existing graphic user interface software, allowing for ease of usage and greater efficiency. From the measurements, the yield of successful qubits for both single and SQUID junctions are 50\%. For the values of oxidation time set in this project, it is also found that longer oxidation time can produce more qubits in the intended range of frequencies. Single qubit measurements are performed to determine the qubit frequency and the coherence times $T_1$ and $T_2^*$ which are useful for subsequent experiments.