Shadow and Light : Casting a Shadow with Light and the Design of Geometric Phase Quantum Logic Gates in Waveguide Systems

Abstract

Shadows are a common and familiar optical effect. We can all easily cast, observe, and characterize them. In our daily experience, they occur with the presence of an illumination source and an opaque object that casts the shadow. However, shadows cast by an opaque object are not the only possibility. In the first project of this thesis, we demonstrate what we call the "laser shadow" effect, where beams of light serve as both illumination source and object to create a new type of shadow. We then characterize the temperature and power dependence of the effect. Finally, we demonstrate how this laser shadow is indeed a shadow by comparing it to a genuine shadow. Creating a quantum computer is a goal at the intersection of both quantum mechanics and computer science. It is of interest because quantum computers have been shown to have an advantage over classical computers in solving certain types of problems. In the second project of this thesis, we design a possible building block for such a quantum computer. The design relies on the "geometric phase", which theory suggests can provide enhanced robustness against errors. We then test our design in simulations of waveguide systems using two material platforms in different coupling regimes. Finally, we propose a practical experiment to take the design out of the computer and test the waveguide system using a physical apparatus.