Parker Ryan C, Joo Jaewoo, Spiller Timothy P
York Centre for Quantum Technologies, Department of Physics, University of York, York YO10 5DD, UK.
School of Mathematics and Physics, University of Portsmouth, Portsmouth PO1 3QL, UK.
Proc Math Phys Eng Sci. 2020 Nov;476(2243):20200237. doi: 10.1098/rspa.2020.0237. Epub 2020 Nov 18.
We propose the use of hybrid entanglement in an entanglement swapping protocol, as means of distributing a Bell state with high fidelity to two parties. The hybrid entanglement used in this work is described as a discrete variable (Fock state) and a continuous variable (cat state super- position) entangled state. We model equal and unequal levels of photonic loss between the two propagating continuous variable modes, before detecting these states via a projective vacuum-one-photon measurement, and the other mode via balanced homodyne detection. We investigate homodyne measurement imperfections, and the associated success probability of the measurement schemes chosen in this protocol. We show that our entanglement swapping scheme is resilient to low levels of photonic losses, as well as low levels of averaged unequal losses between the two propagating modes, and show an improvement in this loss resilience over other hybrid entanglement schemes using coherent state superpositions as the propagating modes. Finally, we conclude that our protocol is suitable for potential quantum networking applications which require two nodes to share entanglement separated over a distance of , when used with a suitable entanglement purification scheme.
我们提议在纠缠交换协议中使用混合纠缠，以此作为向两方高保真度分发贝尔态的手段。本工作中使用的混合纠缠被描述为离散变量（福克态）与连续变量（猫态叠加）的纠缠态。在通过投影真空单光子测量检测其中一个态、通过平衡零差检测检测另一个态之前，我们对两个传播的连续变量模式之间相等和不相等程度的光子损耗进行建模。我们研究零差测量的不完善性以及此协议中所选用测量方案的相关成功概率。我们表明，我们的纠缠交换方案对低水平的光子损耗以及两个传播模式之间低水平的平均不等损耗具有抗性，并且相较于使用相干态叠加作为传播模式的其他混合纠缠方案，在这种损耗抗性方面有所改进。最后，我们得出结论，当与合适的纠缠纯化方案一起使用时，我们的协议适用于需要两个节点在一定距离上共享纠缠的潜在量子网络应用。
