基于轨道角动量的多自由度W态纠缠系统∗

摘要

We propose a method of generating the three-photon W state. The method uses parametric down-conversion process and hybrid entanglement swapping from multiphoton spin-entangled states to multiphoton orbital angular momentum (OAM) entangled states, with the aid of a pair of polarization photons. They generate W state entangled in different degrees of freedom of polarization and OAM with a high-dimensional Hilbert space. By simply changing the methods of generating a polarization-OAM-linear momentum entangled W state. Our method produces two mutually symmetric W states with strong entanglement and high dimension, which is expected to realize the secure communication of extending quantum bits.%提出了一种制备三光子纠缠W态的方案，该方案利用携带轨道角动量为l~的光子(其中l可取(−∞，+∞)的任意整数)可构成无穷维向量空间的特性，采用两种类型的参量下转换，产生轨道角动量-自旋角动量纠缠的两对光子和一对偏振纠缠光子，通过纠缠交换制备三光子多自由度的W态，实现三光子体系纠缠的高维度、大容量量子信息处理。方案采用q-plate相位光学器件和单模光纤等器件制备两个不同自由度(轨道角动量与偏振)混合的W态，并利用计算机全息相位图改进方案制备三个不同自由度(轨道角动量、线动量和偏振)混合的W态。本方案可稳定产生两种等概率互为对称的W态，具有高维度、强纠缠特性与抗比特丢失能力，信息量达log2 m+2比特(m为l的可取值个数)，有望实现可扩容量子比特的安全通信。