Analysis of Photonic Quantum Nodes Based on Single Photon Raman   Interaction
  The long-standing goal of deterministically controlling a single photon using another was recently realized in various experimental settings. Among these, a particularly attractive demonstration relied on single-photon Raman interaction (SPRINT) in a three-level Lambda-system coupled to a single-mode waveguide. Beyond the ability to control the direction of propagation of one photon by the direction of another photon, this scheme has the potential to perform as a passive quantum memory and a universal quantum gate. Relying on interference, this all-optical, coherent scheme requires no additional control fields, and can therefore form the basis for scalable quantum networks composed of passive quantum nodes that interact with each other only with single photon pulses. Here we present an analytical and numerical study of SPRINT, and characterise its limitations and the parameters for optimal operation. Specifically, we study the effect of losses and the presence of multiple excited states. In both cases we discuss strategies for restoring the high fidelity of the device's operation. 
Serge Rosenblum, Adrien Borne and Barak Dayan
quant-ph physics.atom-ph