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Quantum networks crucially rely on the availability of high-quality entangled pairs of qubits, known as entangled links, distributed across distant nodes. Maintaining the quality of these links is a challenging task due to the presence of…

Quantum Physics · Physics 2024-09-04 Bethany Davies , Álvaro G. Iñesta , Stephanie Wehner

Given a finite number $N$ of copies of a qubit state we compute the maximum fidelity that can be attained using joint-measurement protocols for estimating its purity. We prove that in the asymptotic $N\to\infty$ limit, separable-measurement…

Quantum Physics · Physics 2009-11-11 E. Bagan , M. A. Ballester , R. Munoz-Tapia , O. Romero-Isart

The entanglement fidelity provides a measure of how well the entanglement between two subsystems is preserved in a quantum process. By using a simple model we show that in some cases this quantity in its original definition fails in the…

Quantum Physics · Physics 2009-11-13 Yang Xiang , Shi-Jie Xiong

Bipartite entanglement purification is the conversion of copies of weakly entangled pairs shared between two separated parties into a smaller number of strongly entangled shared pairs using only local operations and classical communication.…

Quantum Physics · Physics 2025-11-14 Matthew Barber , Stefano Pirandola

Entanglement purification takes a number of noisy EPR pairs and processes them to produce a smaller number of more reliable pairs. If this is done with only a forward classical side channel, the procedure is equivalent to using a quantum…

Quantum Physics · Physics 2007-11-07 Andris Ambainis , Daniel Gottesman

Entanglement purification protocols play an important role in the distribution of entangled systems, which is necessary for various quantum information processing applications. We consider the effects of photo-detector efficiency and…

Quantum Physics · Physics 2007-05-23 Peter P. Rohde , Timothy C. Ralph , William J. Munro

Since its discovery, the quantum entanglement becomes a promising resource in quantum communication and computation. However, the entanglement is fragile due to the presence of noise in quantum channels. Entanglement purification is a…

Quantum Physics · Physics 2023-04-26 Peishun Yan , Lan Zhou , Wei Zhong , Yubo Sheng

Quantum networks rely on the efficient distribution of entanglement to enable long-distance quantum communication and information processing. A key challenge in these networks is the design of routing protocols capable of maintaining high…

Networking and Internet Architecture · Computer Science 2026-05-25 Javier Vecino Peñas , Ana Fernández-Vilas , Rebeca P. Díaz-Redondo , Sergio Gándara Gándara , Manuel Fernández-Veiga

Entanglement buffers are systems that maintain high-quality entanglement, ensuring it is readily available for consumption when needed. In this work, we study the performance of a two-node buffer, where each node has one long-lived quantum…

Quantum Physics · Physics 2025-02-28 Álvaro G. Iñesta , Bethany Davies , Sounak Kar , Stephanie Wehner

Quantum networks are expected to enhance distributed quantum computing and quantum communication over long distances while providing security dependent upon physical effects rather than mathematical assumptions. Through simulation, we show…

We discuss a specific entanglement distillation scheme under the constraint of finite samples of entangled qubit pairs. It is shown that an iterative process can be explicitly formulated. The average fidelity of this process can be enhanced…

Quantum Physics · Physics 2007-05-23 Stefan Probst-Schendzielorz , Thorsten Bschorr , Matthias Freyberger

The goal of entanglement distillation is to turn a large number of weakly entangled states into a smaller number of highly entangled ones. Practical entanglement distillation schemes offer a tradeoff between the fidelity to the target…

We investigate entanglement detection when the local measurements only nearly correspond to those intended. This corresponds to a scenario in which measurement devices are not perfectly controlled, but nevertheless operate with bounded…

Quantum Physics · Physics 2022-06-22 Simon Morelli , Hayata Yamasaki , Marcus Huber , Armin Tavakoli

We introduce entanglement purification protocols for d-level systems (qudits) with improved efficiency as compared to previous protocols. While we focus on protocols for bipartite systems, we also propose generalizations to multi-partite…

Quantum Physics · Physics 2018-10-17 Jorge Miguel-Ramiro , Wolfgang Dür

Recently emerged as a disruptive networking paradigm, quantum networks rely on the mysterious quantum entanglement to teleport qubits without physically transferring quantum particles. However, the state of quantum systems is extremely…

Quantum Physics · Physics 2024-08-23 Ziyue Jia , Lin Chen

Using holographic idea, we study the entanglement of purification in a field theory with a critical point in intermediate and low temperature regime. This theory includes temperature $T$ as well as chemical potential $\mu$. In the…

High Energy Physics - Theory · Physics 2021-05-05 B. Amrahi , M. Ali-Akbari , M. Asadi

The notion of entanglement fidelity is to measure entanglement preservation through quantum channels. Nevertheless, the amount of entanglement present in a state of a quantum system at any time is measured by quantities known as measures of…

Quantum Physics · Physics 2020-04-07 Vahid Azimi Mousolou

Entanglement purification protocols are fundamental primitives in quantum communication, enabling the distillation of high-quality entanglement using only local operations and classical communication. For large multipartite states, however,…

Quantum Physics · Physics 2026-04-06 Katerina Stloukalova , Jorge Miguel-Ramiro , Wolfgang Dür , Julius Wallnöfer

We develop theoretical and numerical tools for the quantification of entanglement in systems with continuous degrees of freedom. Continuous variable entanglement swapping is introduced and based on this idea we develop methods of…

Quantum Physics · Physics 2009-10-31 S. Parker , S. Bose , M. B. Plenio

We show that thresholds for fault-tolerant quantum computation are solely determined by the quality of single-system operations if one allows for d-dimensional systems with $8 \leq d \leq 32$. Each system serves to store one logical qubit…

Quantum Physics · Physics 2016-08-16 W. Dür , H. -J. Briegel