A Stable Traveling-Wave Optical Parametric Oscillator for Entanglement Protection and Manipulation

This dissertation presents both the theoretical and experimental progress in building sources for both quantum optics and one-way quantum computing. An optical parametric oscillator (OPO) is a source of quantum fields. The quantum fields of an OPO can be squeezed, which is suited for interferometry, and can be entangled, which is necessary for one-way quantum computing.;A traveling-wave OPO was built for research in quantum optics and quantum information. An OPO is a resonant cavity with a nonlinear crystal inside. The nonlinear crystal in the OPO produced twin beams (at 1064 nm) by down converting a pump source (at 532 nm) Like a laser, the OPO can be below or above threshold. The traveling-wave design allowed for the OPO to be pumped in counterpropagating directions to produce twin beam pairs counterpropagating in the cavity. Due to the resonance conditions of the cavity, the forward and backward twin beam pairs were identical. When the OPO was above threshold (240 mW) in the forward direction, the intensity noise of the forward twin beams was reduced by 5.9 dB. The intensity noise for the backward twin beams was reduced by 5.1 dB, when the OPO was above threshold (280 mW).;This OPO is a core component of several sophisticated quantum optics experiments. One such experiment is the creation of a scalable number of 4-mode cluster entangled states in the optical frequency comb of the OPO. A cluster state is an entangled state that is necessary to perform one-way quantum computing. This work presents a detailed theory, an experimental proposal, and exhaustive preliminary experiments towards creating several four-mode cluster states in a single OPO.;The second experiment considered in this dissertation is the protection of entanglement from decoherence by the quantum engineering of the reservoir fluctuations which, once traced over, are responsible for decoherence. It was shown that entangling the reservoirs that interact with initial two entangled physical systems protected the initial entanglement.