论文标题
量子直接通信协议在K-cycle量子步行中使用复发
Quantum direct communication protocol using recurrence in k-cycle quantum walk
论文作者
论文摘要
量子步行在不同量子状态的叠加中发展的能力已被用作量子通信协议中的资源。在某些设置下，众所周知，$ k $ - 循环离散时间量子步行\（dtqw）在每$ t_r $ steps之后都会复发至其初始状态。我们首先提出了一种方案，可以使用$ j $板，轨道角动量\，（OAM）分音机，光学开关和光学延迟线来光学地实现任何$ k $ -cycle dtqw。这纠缠了单个光子的自由度\（dof）的极化程度和绿色oaM。利用$ k $ cycle dtqw的这种复发现象以及在演变过程中产生的纠缠，我们提出了新的量子直接通信协议。 $ k $循环步行中的复发和纠缠分别用于在拟议的协议中分别检索和保护信息。我们调查了针对截距和重新发射攻击的协议的安全性。我们还量化了振幅阻尼和去极化噪声对单个光子极化和OAM DOF之间的复发和相互信息的影响。
The ability of quantum walks to evolve in a superposition of distinct quantum states has been used as a resource in quantum communication protocols. Under certain settings, the $k$-cycle discrete-time quantum walks\,(DTQW) are known to recur to its initial state after every $t_r$ steps. We first present a scheme to optically realize any $k$-cycle DTQW using $J$-plate, orbital angular momentum\,(OAM) sorters, optical switch, and optical delay line. This entangles the polarization and OAM degrees of freedom\,(DoF) of a single photon. Making use of this recurrence phenomena of $k$-cycle DTQW and the entanglement generated during the evolution, we present a new quantum direct communication protocol. The recurrence and entanglement in $k$-cycle walk are effectively used to retrieve and secure the information, respectively, in the proposed protocol. We investigate the security of the protocol against intercept and resend attack. We also quantify the effect of amplitude damping and depolarizing noises on recurrence and mutual information between polarization and OAM DoF of a single photon.
