In this paper, we introduce a new quantum key distribution protocol, which we refer to as polarization-phase (PoP) protocol. In this protocol, two degrees of photonic freedom of the same particle in a hybrid manner are used to encode the information in the format of two- or high-dimensional quantum states (qubits and qudits, respectively). Here, we only discuss the qubit version of the general PoP protocol (we refer to two-dimensional PoP (TD-PoP) protocol) as an interesting extension for the standard BB84 protocol. We investigate the performance of the TD-PoP protocol using infinite-key analysis against restricted individual attacks, i.e. the intercept-resend and photon number splitting attacks, in both ideal single-photon and Poisson (attenuated laser) sources. In addition, we demonstrate that this protocol, despite using two physical dimensions, is simple and fully has empirical implementation capability. Ability to extract two bits of information from each detection event, and increasing the sifting parameter, the secure key rate, and the likelihood of detection of an eavesdropper, are the advantages of the TD-PoP protocol compared to the standard polarization- or phase-encoded BB84 protocol.

中文翻译：

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一种基于极化相位编码的二维量子密钥分发协议

在本文中，我们介绍了一种新的量子密钥分发协议，我们将其称为极化相位（PoP）协议。在该协议中，以混合方式使用同一粒子的两个光子自由度以二维或高维量子态（分别为量子位和量子点）的格式对信息进行编码。在这里，我们只讨论通用 PoP 协议的量子比特版本（我们称为二维 PoP (TD-PoP) 协议）作为标准 BB84 协议的有趣扩展。我们在理想的单光子和泊松（衰减激光）源中使用无限密钥分析来研究 TD-PoP 协议对受限个体攻击（即拦截重发和光子数分裂攻击）的性能。此外，我们证明了该协议，尽管使用了两个物理维度，简单，完全具备经验实现能力。能够从每个检测事件中提取两位信息，并增加筛选参数、安全密钥速率和检测窃听者的可能性，是 TD-PoP 协议与标准极化或相位相比的优势编码的 BB84 协议。