Building a Qubit

Dave Bacon

Nathalie P. de Leon

Sebastian Pauka

Throughout this Ph.D., the quest to build a quantum computer has accelerated, driven by ever-improving fidelities of conventional qubits and the development of new technologies that promise topologically protected qubits with the potential for lifetimes that exceed those of comparable conventional qubits. As such, there has been an explosion of interest in the design of an architecture for a quantum computer. This design would have to include high-quality qubits at the bottom of the stack, be extensible, and allow the layout of many qubits with scalable methods for readout and control of the entire device. Furthermore, the whole experimental infrastructure must handle the requirements for parallel operation of many qubits in the system. Hence the crux of this thesis: to design an architecture for a semiconductor-based quantum computer that encompasses all the elements that would be required to build a large scale quantum machine, and investigate the individual these elements at each layer of this stack, from qubit to readout to control.

Michel Le Bellac

Graham P. Collins

Z Thrailkill, S Kennerly, A Tyler +1 more

The superconducting Josephson junction has been demonstrated to be a strong candidate for building quantum bits or "qubits" which are the components of a future quantum computer. In recent years, considerable theoretical and experimental effort have been focused on studying quantum properties of single qubits and two coupled solid-state qubits. We present results of numerical simulations of the energy spectra of more three phase qubits that are capacitively-coupled in different configurations. We discuss the ensuing entanglement between component qubits as manifested in avoided crossings and how these may play a role in building gates and transmitting qubit state information.