Simple Schemes of CQED for Realizing Swap, Entangling and CNOT Quantum Gates

We consider two cavities which are spatially separated and connected by an optical fibre. There are multi two-level atoms in each of the cavities. The atoms resonantly interact with the cavity fields but there is no direct interaction between the atoms. We show that perfect swap and entangling quantum gates can be realised between the two atoms clusters if modes of the electromagnetic field in the cavities and fibre are initially not excited. Compared with the single atom scheme, we find that the multi-atom scheme can speed up the quantum gates by a factor √N where N is number of the atoms in each of the cavities. We also consider the case where two two-level atoms in distant cavities that are coupled by an optical fibre. We find if both of the atoms interact resonantly with the fields, a highly reliable CNOT gate can be achieved within much less operation time than that of the non- resonant case. The sensibility of these gates to various parameters contained in the models under consideration is also investigated.

Simple Schemes of CQED for Realizing Swap, Entangling and CNOT Quantum Gates