Dense coding or super-dense coding in the case of high-dimension quantum states between two parties and multi-parties has been studied in this paper. We construct explicitly the measurement basis and the forms of the single-body unitary operations corresponding to the basis chosen, and the rules for selecting the one-body unitary operations in a multi-party case.
Characterizing pairwise swapping capabilities of dense coding channels
Harish-Chandra Research Institute（哈里什-钱德拉研究所）；Homi Bhabha National Institute（霍米·巴巴国立研究所）；International Institute of Information Technology Hyderabad（海得拉巴国际信息技术学院）；Birla Institute of Technology and Science, Pilani, Hyderabad Campus（比拉理工学院皮拉尼校区海得拉巴分校）
Secret sharing is a multi-party cryptographic primitive that can be applied to a network of partially distrustful parties for encrypting data that is both sensitive (it must remain secure) and important (it must not be lost or destroyed). When sharing classical secrets (as opposed to quantum states), one can distinguish between protocols that leverage bi-partite quantum key distribution (QKD) and those that exploit multi-partite entanglement. The latter class are known to be vulnerable to so-called participant attacks and, while progress has been made recently, there is currently no analysis t…
The states of W-class as shared resources for perfect teleportation and superdense coding
我们知道，三量子比特系统的态有两类：GHZ类和W类。本文考虑W类态的隐形传态和超密集编码，并将其推广到多粒子系统。首先，我们描述了两个转换的共享资源的隐形传态和超密集编码，这使得许多新的协议，从一些已知的。作为这些变换的应用，我们得到了W类态适合于理想隐形传态和超密编码的一个充要条件。作为另一个应用，我们发现状态$|W>_{123}={1/2}(|100>_{123}+|010>_{123}+\sqrt{2}|001>_{123})$可以通过发送两个量子比特来传输三个经典比特，这是P.Agrawal和A. Pati [Phys. Rev. A待出版]。我们将W类的态推广到高维的多量子比特系统和多粒子系统。我们提出了两个利用多量子比特系统的W态进行隐形传态和超密集编码的协议，推广了P.Agrawal和A.帕蒂我们得到了将多量子比特系统的W态分割成两个子系统的最优方法，使得它们之间的纠缠达到最大值。
In this paper, we put forward a multi-party quantum private comparison (MQPC) protocol with two semi-honest third parties (TPs) by adopting d-dimensional Bell states, which can judge the size relationship of private integers from more than two users within one execution of protocol. Each TP is permitted to misbehave on her own but cannot collude with others. In the proposed MQPC protocol, TPs are only required to apply d-dimensional single-particle measurements rather than d-dimensional Bell state measurements. There are no quantum entanglement swapping and unitary operations required in the p…
Let $\mathcal{B}_d$ be the unital $C^*$-algebra generated by the elements $u_{jk}, \, 0 \le i, j \le d-1$, satisfying the relations that $[u_{j,k}]$ is a unitary operator, and let $C^*(\mathbb{F}_{d^2})$ be the full group $C^*$-algebra of free group of $d^2$ generators. Based on the idea of teleportation and super-dense coding in quantum information theory, we exhibit the two $*$-isomorphisms $M_d(C^*(\mathbb{F}_{d^2}))\cong \mathcal{B}_d\rtimes \mathbb{Z}_d\rtimes \mathbb{Z}_d$ and $M_d(\mathcal{B}_d)\cong C^*(\mathbb{F}_{d^2})\rtimes \mathbb{Z}_d\rtimes \mathbb{Z}_d$, for certain actions of …
The domain of allowed von Neumann entropies of a holographic field theory carves out a polyhedral cone -- the holographic entropy cone -- in entropy space. Such polyhedral cones are characterized by their extreme rays. For an arbitrary number of parties, it is known that the so-called perfect tensors are extreme rays. In this work, we constrain the form of the remaining extreme rays by showing that they correspond to geometries with vanishing mutual information between any two parties, ensuring the absence of Bell pair type entanglement between them. This is tantamount to proving that besides …
