Analysis of Cavity-QED-Based Single Photon Generation toward Scalable Quantum Information Processing

Deterministic generation of single photons, which is a key ingredient to realize optical quantum information processing, has been experimentally demonstrated by making use of cavity QED systems with various settings so far. To combine such single photon generators with other elementary components such as quantum gates, it is important to understand the characteristics of the output photons and to choose the optimal parameters by considering the scalability, which have not been sufficiently discussed yet. Here, to tackle the above problem, we analyze two single photon generation schemes. We consider a scheme which relies on stimulated Raman adiabatic passage (STIRAP) in a three-level system, and we compare this with a scheme which relies on the Purcell effect in a two-level system. We numerically simulate the process with a wide range of parameters, where the adiabatic condition is not always satisfied. We also derive a concise analytic expression for the photon loss probability in the STIRAP case. Finally, as a practical example, we show that nanofiber cavities¹ have the capability to generate photons with high probability even with overwhelmingly large cavity internal losses compared to free-space Fabry-Perot cavities.
¹S. Kato and T. Aoki, Phys. Rev. Lett. 115, 093603 (2015).