Hybrid quantum repeater based on dispersive CQED interactions between matter qubits and bright coherent light
Hybrid quantum repeater based on dispersive CQED interactions between matter qubits and bright coherent light
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DOI：
10.1088/1367-2630/8/9/184
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发表时间：
2006-09-08
影响因子：
3.3
通讯作者：
Yamamoto, Y.
中科院分区：
文献类型：
--
作者：
Ladd, T. D.;van Loock, P.;Yamamoto, Y.
我们描述了一个长距离量子纠缠分布的系统，在该系统中，具有大平均光子数的相干光与光学腔中的单个远失谐原子或半导体杂质色散相互作用。纠缠是预示着零差检测使用第二个明亮的光脉冲的相位参考。使用明亮的脉冲导致高的成功概率的纠缠的产生，在较低的初始保真度的成本。这种保真度可以通过使用相同的物理资源实现的纠缠纯化技术来提高。与使用单光子或弱相干脉冲与现实探测器的预示性纠缠方案相比，对更多纯化步骤的需求得到了很好的补偿。较低的初始保真度的主要原因是光纤损耗;然而，在色散原子-腔相互作用期间的自发衰减和腔损耗也会损害性能。我们表明，这些影响可能会被最小化的发射极腔系统中的弱耦合制度，只要谐振珀塞尔因子大于1，腔是过耦合，和光脉冲是足够长的。我们支持这一主张的数值，半经典计算使用参数为三个现实的系统：光学明亮的施主结合杂质，如F-19：ZnSe与中等Q微腔，光学暗淡的P-31：Si系统与高Q微腔，和捕获的离子在大，但非常高Q腔。
We describe a system for long-distance distribution of quantum entanglement, in which coherent light with large average photon number interacts dispersively with single, far-detuned atoms or semiconductor impurities in optical cavities. Entanglement is heralded by homodyne detection using a second bright light pulse for phase reference. The use of bright pulses leads to a high success probability for the generation of entanglement, at the cost of a lower initial fidelity. This fidelity may be boosted by entanglement purification techniques, implemented with the same physical resources. The need for more purification steps is well compensated for by the increased probability of success when compared to heralded entanglement schemes using single photons or weak coherent pulses with realistic detectors. The principal cause of the lower initial fidelity is fibre loss; however, spontaneous decay and cavity losses during the dispersive atom - cavity interactions can also impair performance. We show that these effects may be minimized for emitter-cavity systems in the weak-coupling regime as long as the resonant Purcell factor is larger than one, the cavity is over-coupled, and the optical pulses are sufficiently long. We support this claim with numerical, semiclassical calculations using parameters for three realistic systems: optically bright donor-bound impurities such as F-19 : ZnSe with a moderate-Q microcavity, the optically dim P-31 : Si system with a high-Q microcavity, and trapped ions in large but very high-Q cavities.