Input-output Analysis of Quantum Finite-level Systems in Response to Single Photon States
Yu Liang Pan, Guo‐Feng Zhang, M. R. James · arXiv (Cornell University) · 2014
Single photon states, which carry quantum information and coherently interact with quantum systems, are vital to the realization of all-optical quantum networks and quantum memory. In this paper we derive the conditions that enable an exact analysis of the response of passive quantum finite-level systems under the weak driving of single photon input. We show that when a class of finite level systems is driven by single photon inputs, expressions for the output states may be derived exactly using linear systems transfer functions. This removes the need for physical approximations such as weak excitation limit in the analysis of quantum nonlinear systems under single photon driving. We apply this theory to the analysis of a single photon switch. The input-output relations are consistent with the existing results in the study of few photon transport through finite-level systems.