UROP Proceedings 2021-22

School of Science Department of Physics 58 Materials Characterisation of Superconducting Thin Films for Quantum Computing Applications Supervisor: JAECK Berthold / PHYS Student: LEUNG Ka Wun Casey / PHYS Course: UROP1100, Fall Superconducting qubits is one of the most promising approaches for quantum computing and they are based on fabrications of superconducting thin films on microwave circuits. To improve the performance of the qubits, the thin film is optimized by reducing the oxides and changing the superconducting materials. In this project, we investigate three superconducting thin films, namely aluminium thin film, tantalum thin film, and High Entropy Alloys thin film. The Tantalum thin film is fabricated through RF sputtering and high entropy alloys are fabricated through DC sputtering. The goal of this project is to characterise the properties of various superconducting thin films. To characterise the thin film, we use difference microscopic and spectroscopy techniques such as X-ray diffraction, Atomic Force Microscopy, and X-ray photoelectron spectroscopy (XPS). This allow us to characterize the metal and the oxides on the surface, which is the key of microwave loss of qubit resonator. Epitaxial Growth of Magnetic Kagome Metals Supervisor: JAECK Berthold / PHYS Student: LIN Yi-hsin / PHYS-IRE Course: UROP1100, Summer Kagome metals have been identified as a promising class of materials hosting rich phenomenon, including superconductivity and topological flat band. However, most investigations were done on bulk crystal due to the difficulty of growing thin film directly on substrate. Introducing platinum buffer layer in between can facilitate the uniform atomic layer growth of two-dimensional Kagome metals, paving the way for exploring more novel physical phenomenon. This report introduces the process of growing platinum buffer layer from substrate preparation, along with various techniques and instruments required for material characterization. Electromagnetic and Acoustic Metasurfaces Supervisor: LI Jensen Tsan Hang / PHYS Student: CHEUNG Ka Ho / SSCI Course: UROP1000, Summer Metamaterials have unique electromagnetic properties unlike conventional materials occur in nature due to their artificially designed volumetric structures. Metamaterials gave rise to many and on-going researches such as invisibility, superlenses, medical devices, etc. However, the production of the nano-fabrication process on metamaterials is expensive and complicated. Hence, metasurface, a two-dimensional thin layer nano-structured material is introduced as a cheaper and simpler alternative approach to optical experiments. Here, we investigate the components and the coincident data in a two photons imaging setup. By studying the whole process flow of the experimental setup, we can have a clearer objective and acknowledgement of the reason behind the components of the setup as well.