Reconfigurable Quantum Materials and Quantum Sensing

Abstract: Understanding quantum materials and developing quantum hardware are consistent goals and challenges for quantum information science. Among the materials, van der Waals (vdW) materials and reconfigurable complex oxides show great potential to support the route by providing plentiful properties. In the thesis, I show my efforts in establishing a new method of ultra-low voltage electron-beam lithography (ULV-EBL) to create reconfigurable nanostructures at complex oxide interfaces. Compared to previous reports that utilize conductive atomic force microscope (c-AFM) lithography, this approach can provide comparable resolution (10 nm) at write speeds (10 mm/s) that are up to 10000 faster than c-AFM. The writing technique is non-destructive, and the conductive state is reversible via prolonged exposure to air. I demonstrate how reprogrammable quantum materials can be achieved by gating vdW stacks with reprogrammable complex-oxide heterostructures ULV-EBL. This technique for nanoscale gating of vdW materials has the potential for instantiating a wide range of 2D Fermi-Hubbard models, and for creating emergent properties such as novel magnetic and superconducting phases. For efforts towards quantum sensing, surface acoustic wave (SAW) is used to detect quantum paraelectric regime phase transitions and is shown to be coupled with ferroelastic domains.