Phys10 - Artificial atoms driven by strong periodic fields

Two-state systems are very important in quantum mechanics. They are used extensively to study various aspects of quantum dynamics. In addition, they are the building blocks for the implementation of quantum computing and other quantum technologies.

The ability to control the evolution of a quantum two-state system is essential both for fundamental investigations and applications. The usual approach to state control relies on the application of a periodic stimulus, with a frequency corresponding to the difference in energy between the ground and excited state. The periodic drive amplitude is usually small, in which case the dynamics is simple, consisting of an oscillation between the two quantum states. We study a regime where the driving amplitude is large, leading to new types of dynamics. Experiments are performed using artificial atoms, based on superconducting nanostructures, which are ideally suitable to observe strong driving dynamics. In this regime the quantum dynamics is described using the framework of Floquet theory, that emphasizes the periodic driving and applies at any driving amplitude. This study has applications to quantum computers, where strong driving has the potential to achieve higher fidelity than in conventional approaches.