Speaker: Benjamin Harpt, Physics PhD Graduate Student
Abstract: Quantum computers offer the potential to solve problems beyond the reach of classical computers by harnessing fundamentally different physics. Today, researchers worldwide are racing to develop quantum computers that are both controllable and scalable, utilizing a wide range of hardware approaches to encode quantum information. Superconducting circuits and semiconductor quantum dots are, individually, two of the leading qubit platforms for building solid-state quantum processors; combining the strengths of both materials in hybrid devices opens up new possibilities for quantum computing architectures. This dissertation explores key aspects of superconductor-semiconductor hybrid systems for quantum computing, and is structured in three parts. Part I presents an in-depth overview of silicon quantum-dot qubits, with a focus on experiments investigating crosstalk between exchange-only spin qubits. Part II addresses the integration of these qubits with superconducting resonators for readout and long-range entanglement. Using a quantum-dot device coupled to a vertically integrated resonator, we demonstrate an unconventional electron-photon interaction mechanism and show how it can be utilized for qubit readout and spectroscopy. Finally, Part III examines superconductor-semiconductor hybrid junctions and their qubit applications, detailing the development of superconducting alloys tailored for germanium-based hybrid devices. Together, these findings advance our understanding and introduce new techniques for developing hybrid quantum technologies.