Entangling light in high dimensions

Abstract

Quantum entanglement is a fundamental trait of quantum mechanics that causes the information about the properties of two (or more) objects to be inextricably linked. When a measurement on one of the objects is performed, the state of the other object is immediately altered, even when these objects are separated at arbitrary distances. In this thesis, we explore the rich properties of entanglement in a high-dimensional mode space. Experimentally, we have implemented the high dimensionality by use of the orbital-angular-momentum degree of freedom of entangled photon pairs. The emphasis is on the question how to quantify the dimensionality of the entanglement as measured in an experiment. We introduce the Shannon dimensionality as a useful quantifier of measured entanglement. Furthermore, we discuss various production methods of optical phase plates, which we use to manipulate the orbital-angular-momentum states of light. Finally, we present an experimental feasibility study on the potential of orbital-angular-momentum entanglement for free-space quantum communication through the atmosphere