Towards Building a Photon-Photon Gate Using an Atomic Double-Cavity QED System*

There are significant efforts worldwide to build a quantum internet that can distribute and process entangled photons. It has been envisioned that second and third generation quantum communication networks should be assisted with photonic quantum gates [1]. Constructing a photonic quantum gate is a non-trivial task, however the cavity QED platforms has been shown to be a realistic pathway for its realizations [2]. We have constructed a platform that combines the ideas of two leading elements of quantum technology, namely collective enhancement effects in a cold rubidium 87 atomic ensemble in a magneto-optical trap (MOT). For the first time, we show two Fabry-Perot cavities coupled to the same atomic ensemble, forming a double cavity QED systems. We report our recent experimental progress, demonstrating vacuum Rabi splitting (VRS) simultaneously in both cavities, each on resonance with the D2 line, F=2 to F'=3 transition. We also present our predictions based on a full master equation simulation of the system, showing strong evidence that quantum-level cross-talk between the cavities is achievable. 

[1] Sci Rep 6, 20463 (2016). 

[2] Nature Physics, 15, 124, (2019)