Dynamics of Charge and Spin Qubits Under Strong Driving

Abstract

Quantum dots are fruitful systems for studying charge and spin dynamics at the single electron level. In this thesis we explore electron dynamics under strong microwave driving. This reveals a range of interesting non-equlibrium dynamics. We first study Landau-Zener-Stückelberg-Majorana (LZSM) dynamics in a single electron charge qubit. Here we observe the expected multi-photon transition fringes and phenomena such as coherent destruction of tunneling. Next we explore the role of LZSM transitions in spin dynamics in InAs nanowires. Early studies showed that unexpected harmonic driving exists in these systems. Here we conclusively show through a combination of experiment and theory that the harmonic driving is due to a multi-level Landau-Zener-Stückelberg-Majorana interference. Finally we study the photon emission processes from a driven double quantum dot. Here we find an intriguing interference pattern between gain and loss that we attribute to effective population inversion explained by Floquet theory.