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We consider the distribution of secret keys, both in a bipartite and a multipartite (conference) setting, via a quantum network and establish a framework to obtain bounds on the achievable rates. We show that any multipartite private…

Quantum Physics · Physics 2021-11-01 Siddhartha Das , Stefan Bäuml , Marek Winczewski , Karol Horodecki

Shor and Preskill have provided a simple proof of security of the standard quantum key distribution scheme by Bennett and Brassard (BB84) by demonstrating a connection between key distribution and entanglement purification protocols with…

Quantum Physics · Physics 2007-05-23 Daniel Gottesman , Hoi-Kwong Lo

We study the separability of permutationally symmetric quantum states. We show that for bipartite symmetric systems most of the relevant entanglement criteria coincide. However, we provide a method to generate examples of bound entangled…

Quantum Physics · Physics 2009-05-12 Geza Toth , Otfried Gühne

Distribution and distillation of entanglement over quantum networks is a basic task for Quantum Internet applications. A fundamental question is then to determine the ultimate performance of entanglement distribution over a given network.…

Quantum Physics · Physics 2020-08-17 Masahiro Takeoka , Eneet Kaur , Wojciech Roga , Mark M. Wilde

Starting from several copies of bipartite noisy entangled states, we design a global and optimal local measurement-based protocol in one- and two-dimensional lattices by which any two or more prefix sites can be connected via entanglement.…

Quantum Physics · Physics 2021-01-04 Ratul Banerjee , Srijon Ghosh , Shiladitya Mal , Aditi Sen De

For linear combinations of quantum product averages in an arbitrary bipartite state, we derive new quantum Bell-form and CHSH-form inequalities with the right-hand sides expressed in terms of a bipartite state. This allows us to specify in…

Quantum Physics · Physics 2011-01-04 Elena R. Loubenets

A quantum key distribution protocol is proposed that is a variation of BB84 that provides raw key generation from correlations that violate a Bell-type inequality for single qubit systems and not entangled pairs. Additionally, it 1) is…

Quantum Physics · Physics 2020-03-24 Radha Pyari Sandhir

We consider quantum key distribution (QKD) and entanglement distribution using a single-sender multiple-receiver pure-loss bosonic broadcast channel. We determine the unconstrained capacity region for the distillation of bipartite…

Quantum Physics · Physics 2018-03-13 Masahiro Takeoka , Kaushik P. Seshadreesan , Mark M. Wilde

Entanglement is a fundamental resource for quantum information processing. In its pure form, it allows quantum teleportation and sharing classical secrets. Realistic quantum states are noisy and their usefulness is only partially…

Quantum Physics · Physics 2014-04-15 Maris Ozols , Graeme Smith , John A. Smolin

In this paper, we investigate properties of some multi-particle entangled states and, from the properties applying the secret sharing present a new type of quantum key distribution protocols as generalization of quantum key distribution…

Quantum Physics · Physics 2007-05-23 Sora Choi , Jinsoo Kim , Dong Pyo Chi

We investigate the task of conference key agreement in near-term quantum networks, where the nodes are connected by sources of bipartite entangled states, under the class of local operations not requiring quantum memory. We derive upper…

Quantum Physics · Physics 2026-05-19 Justus Neumann , Hermann Kampermann , Dagmar Bruß , Anton Trushechkin

The Quantum Key Distribution protocol can encode a single quantum state and implements an information-theoretically secure key distribution protocol in communication. In the actual QKD experimental system, there are usually two encoding…

Quantum Physics · Physics 2020-08-26 Gao Feifei , Li Zhihui , Liu Chengji , Han Duo

We investigate the security bounds of quantum cryptographic protocols using $d$-level systems. In particular, we focus on schemes that use two mutually unbiased bases, thus extending the BB84 quantum key distribution scheme to higher…

Quantum Physics · Physics 2007-05-23 Georgios M. Nikolopoulos , Gernot Alber

We present three quantum key distribution protocols using entangled state. In the first two protocols, all Einstein-Podolsky-Rosen pairs are used to distribute a secret key except those chosen for eavesdropping check, because the…

Quantum Physics · Physics 2007-05-23 Jian Wang , Quan Zhang , Chao-jing Tang

After analysing the main quantum secret sharing protocol based on the entanglement states, we propose an idea to directly encode the qubit of quantum key distributions, and then present a quantum secret sharing scheme where only product…

Quantum Physics · Physics 2009-11-07 Guo-Ping Guo , Guang-Can Guo

Recently it has been shown that quantum cryptography beyond pure entanglement distillation is possible and a paradigm for the associated protocols has been established. Here we systematically generalize the whole paradigm to the…

Quantum Physics · Physics 2015-05-13 Remigiusz Augusiak , Pawel Horodecki

We study the explicit relation between violation of Bell inequalities and bipartite distillability of multi-qubit states. It has been shown that even though for $N\ge 8$ there exist $N$-qubit bound entangled states which violates a Bell…

Quantum Physics · Physics 2009-11-13 Soojoon Lee , Jinhyoung Lee , Jaewan Kim

Recently, a technique known as quantum symmetry test has gained increasing attention for detecting bipartite entanglement in pure quantum states. In this work we show that, beyond qualitative detection, a family of well-defined measures of…

Quantum Physics · Physics 2025-11-12 Xiaoyu Liu , Jordi Tura , Albert Rico

We consider distillation of entanglement from two qubit states which are mixtures of three mutually orthogonal states: two pure entangled states and one pure product state. We distill entanglement from such states by projecting n copies of…

We study the relation between violation of Bell inequalities and distillability properties of quantum states. Recently, D\"ur has shown that there are some multiparticle bound entangled states, non-separable and non-distillable, that…

Quantum Physics · Physics 2009-11-07 A. Acin