Quantum information processing with superconducting qubits

Quantum Information Processing with Superconducting Qubits Jerry Moy Chow 2010 This thesis describes the theoretical framework, implementation, and measurements of a quantum processor comprised of superconducting qubits coupled in the circuit quantum electrodynamics (QED) architecture. In the realization of circuit QED, two superconducting ‘transmon’ charge qubits are capacitively coupled to a one-dimensional microwave transmission line resonator which serves as a quantum bus. Single-qubit rotations can be applied through the resonator and their operation is characterized using various benchmarking techniques. Through a virtual photon interaction via the quantum bus, the two qubits can coherently swap a single excitation. A separate two-qubit conditional phase interaction is also observed which is attributable to an interaction in the two-excitation manifold of the transmons. Furthermore, the same quantum bus which couples the qubits can be used as a joint detector of the full two-qubit quantum state. Entanglement witnesses and a violation of a Bell-type inequality are found using this joint detector on highly entangled states. Finally, combining the single-qubit rotations, conditional phase interaction, and joint readout, allows the realization and characterization of simple quantum algorithms, specifically the Deutsch-Jozsa and Grover’s search algorithms.