Tools and Methods for the Distillation of Entanglement in Continuous Variable Quantum Optics

Doctoral Thesis / Dissertation from the year 2008 in the subject Physics - Optics, grade: none, Imperial College London (Department of Physics (Quantum Optics and Laser Science)), course: Tools and Methods for the Distillation of Entanglement in Continuous Variable Quantum Optics, language: English, comment: the thesis is also available at http://alvarofeito.com/articles/thesis/thesis.pdf , abstract: Entanglement is a crucial resource to process and transmit information surpassing the limits of what is possible in classical physics. However environmental noise (or decoherence) puts limits on the performance quantum states can deliver. To overcome these shortcomings, distillation offers a protocol in which local operations on a number of states deliver a strongly entangled state (with little noise). In the broad field of quantum optics the continuous variables of light have been studied for over half a century. This grants the existence of numerous mathematical and experimental tools suitable to explore distillation. The development of some tools for the practical realization of such protocols constitutes the core of this research. The first part of the thesis presents improvements to existing protocols aimed at optimizing optical resources and enhancing success probabilities. To this end I study new configurations of existing protocols and evaluate the advantages of using measurement devices with higher efficiencies. The collaboration with The Ultra Fast Group at the University of Oxford has lead to the first steps towards the experimental implementation of the aforementioned ideas. Many unanswered questions were met along the way: Is the purity of these optical states sufficient for distillation? Are these measuring devices operating in the quantum regime and if so how well? How could one rigorously characterize an entanglement increase in a continuous vari- ables experiment? The second part of this thesis deals with the theoretical tools necessary to answer thes