Quantum Noise & Actuator Based Control in Spin Ensembles

Abstract

This thesis is divided into three parts. In the first part, the protection offered by decoherence free subspaces is quantified and compared against unprotected spaces by means of noise spectroscopy. In the second part, decoherence is studied in two kinds of engineered systems, one model for phase decoherence and the other for spin flip decoherence. In both models, the combination of two noise sources viz. stochastic kicks and temporally randomized flip operations, is shown to lead to frustration of decoherence under certain resonant conditions. Finally, in the third part, the realization of a universal set of gates on a spectroscopically indistinguishable pair of nuclear spins is demonstrated, facilitating improved decoherence free subspaces.