A photon-photon quantum gate based on Rydberg interactions in a cavity

本文的目标是在中等精细度的光学谐振腔中实现基于电磁感应透明和里德伯阻塞的光子-光子控制的非量子门。这种以前未实现的方案结合了里德伯阻塞的优点和光学谐振器提供的优点。我们对实际参数进行了估计，预计在本提案的资助期内，门效率可以达到50%以上。这是一个重大的改进，相对于以前证明的效率高达11%的线性光量子计算，5%的谐振器中的单个原子，和0.5%至8%的自由空间里德伯门。超过50%的预计效率是附近的点，在没有后选择的纠缠双光子状态的生产可以实现和线性光学贝尔状态分析器的基本限制优于。从长远来看，甚至更高的效率将成为可能。这将允许它产生越来越多光子的纠缠态。高性能的光子-光子门将有助于量子中继器中高性能的光子贝尔态探测，并有可能用于量子计算。

The objective of this proposal is to realize a photon-photon controlled NOT quantum gate based on electromagnetically induced transparency and Rydberg blockade inside an optical resonator of moderate finesse. This previously unimplemented scheme combines the advantages of Rydberg blockade with the advantages offered by optical resonators. We made estimates for realistic parameters, which predict that a gate efficiency above 50% can be reached within the funding period of this proposal. This is a major improvement relative to the previously demonstrated efficiencies of up to 11% in linear optical quantum computing, 5% for a single atom in a resonator, and 0.5% to 8% for a free-space Rydberg gate. The projected efficiency above 50% is near the point where production of an entangled two-photon state without postselection can be realized and where the fundamental limit for linear-optical Bell-state analyzers is outperformed. In the long run, even higher efficiencies will come into reach. This will allow it to produce entangled states of larger and larger numbers of photons. A high performance photon-photon gate would be useful for high-performance photonic Bell-state detection in quantum repeaters, and potentially for quantum computation.