Preparation of bell states with controlled white noise

Abstract

We report two methods for producing Bell States with an arbitrary amount of white noise. White noise in this context refers to controlled admixtures of unpolarized light. Our methods differ from previous experiments in that we use the minimum necessary elements for generating a Bell state by c-w spontaneous parametric down conversion. We also investigated the spectral properties of a mixed state and show that one of our methods introduces irreversible noise into the Bell state, making a permanent mixed state. © Nauka/Interperiodica 2006.