Superconducting persistent-current qubits are quantum-coherent artificial atoms with multiple, tunable energy levels. In the presence of large-amplitude harmonic excitation, the qubit state can be driven through one or more of the constituent energy-level avoided crossings. The resulting Landau-Zener-Stueckelberg (LZS) transitions mediate a rich array of quantum-coherent phenomena. We review here three experimental works based on LZS transitions: Mach-Zehnder-type interferometry between repeated LZS transitions, microwave-induced cooling, and amplitude spectroscopy. These experiments exhibit a remarkable agreement with theory, and are extensible to other solid-state and atomic qubit modalities. We anticipate they will find application to qubit state-preparation and control methods for quantum information science and technology.
@article{arxiv.0906.0185,
title = {Large-amplitude driving of a superconducting artificial atom: Interferometry, cooling, and amplitude spectroscopy},
author = {William D. Oliver and Sergio O. Valenzuela},
journal= {arXiv preprint arXiv:0906.0185},
year = {2009}
}