Experiments towards manipulation of quantum states of a Josephson junction using superconducting integrated circuits.

摘要

The quantum mechanics of Josephson junctions at millikelvin temperatures provides a foundation of research upon which my thesis is based. Macroscopic quantum tunneling from discrete energy levels in superconducting tunnel junctions is a phenomenon that has intrigued physicists by allowing observations of coherent macroscopic behavior in a solid-state system. The work that I present relies upon demonstrating energy level quantization by observing macroscopic quantum tunneling of Josephson junctions. I also present spectroscopy of two coupled macroscopic quantum systems by frequency domain experiments.; The current excitement about the realization of a quantum computer is spurred on by the promising results from Josephson junction base superconducting quantum bits (qubits) and has motivated efforts to place novel technologies on an integrated circuit for control and read-out of these qubits. Integration of superconducting digital technology, Rapid Single Flux Quantum (RSFQ) logic/memory, leads the field towards the goals of high-speed, complex and cost effective development of qubit-classical interfacing. The goal of this project is to develop realizable qubit-RSFQ prototypes that will eventually become part of a large-scale quantum based computer. What is essential is the preservation or at least maximization of the coherent quantum dynamics while extracting information from the system via classical methods. A working understanding of qubits gained from my experiments gives an understanding of the complexities and concerns that go into integrating these two systems. I present work towards creating a compatible RSFQ controlled qubit experiment.