Analysis of atom-photon quantum interface with intracavity Rydberg-blocked atomic ensemble via two-photon transition

Recently, significant effort has been devoted to the study of atom-photon quantum interfaces using intracavity Rydberg-blocked atomic ensembles, which may serve as the platform for many essential quantum information processing tasks. In this paper, we use a theoretical analysis of this platform where the ground-Rydberg transition is realized by a two-photon transition, and we report our recent findings regarding the Jaynes-Cummings model on optical domain and robust atom-photon quantum gates. Our implementation with typical alkali atoms, such as Rb or Cs, requires an optical cavity of moderately high finesse and the condition that the cold atomic ensemble is well within the Rydberg-blockade radius. The analysis focuses on the atomic ensemble's collective coupling to the quantized optical field in the cavity mode, and we demonstrate its capability to serve as a controlled-PHASE gate between photonic qubit and matter qubit, where the photonic qubit is endowed with a reasonably wide frequency tuning range. The detrimental effects associated with several major decoherence factors in this system are also considered in the analysis. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement