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We consider problems of distributing high-fidelity entangled states across nodes of a quantum network. We consider a repeater-based network architecture with entanglement swapping (fusion) operations for generating long-distance…

Quantum Physics · Physics 2025-03-25 Xiaojie Fan , Yukun Yang , Himanshu Gupta , C. R. Ramakrishnan

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

In this paper, we consider the problem of entanglement verification across the quantum memories of any two nodes of a quantum network. Its solution can be a means for detecting (albeit not preventing) the presence of intruders that have…

Quantum Physics · Physics 2020-04-17 Michele Amoretti , Stefano Carretta

A key ingredient of quantum repeaters is entanglement distillation, i.e., the generation of high-fidelity entangled qubits from a larger set of pairs with lower fidelity. Here, we present entanglement distillation protocols based on qubit…

Preserving multipartite entanglement amidst decoherence poses a pivotal challenge in quantum information processing. However, assessing multipartite entanglement in mixed states amid decoherence presenting a formidable task. Employing…

Quantum Physics · Physics 2026-03-16 Sovik Roy , Md. Manirul Ali , Abhijit Mandal , Chandrashekar Radhakrishnan

Recently Galv\~{a}o and Hardy have shown that quantum cloning can improve the performance of some quantum computation tasks. However such performance enhancement is possible only if quantum correlations survive the cloning process. We…

Quantum Physics · Physics 2007-05-23 Paweł Masiak

We study the limits of bipartite entanglement distribution using a chain of quantum repeaters that have quantum memories. To generate end-to-end entanglement, each node can attempt the generation of an entangled link with a neighbor, or…

Quantum Physics · Physics 2023-05-11 Álvaro G. Iñesta , Gayane Vardoyan , Lara Scavuzzo , Stephanie Wehner

Reservoir computing is a promising neuromorphic paradigm, and its quantum implementation using spin networks has shown some advantage when entanglement is present. Here, we consider a distributed scenario in which two distinct input time…

Quantum Physics · Physics 2025-11-10 Sareh Askari , Youssef Kora , Christoph Simon

Quantitative characterization of two-qubit entanglement purification protocols is introduced. Our approach is based on the concurrence and the hit-and-run algorithm applied to the convex set of all two-qubit states. We demonstrate that…

Quantum Physics · Physics 2024-09-04 Francesco Preti , József Zsolt Bernád

Quantum network applications impose a variety of requirements on entanglement resources in terms of rate, fidelity, latency, and more. The repeaters in the quantum network must combine good methods for entanglement generation, effective…

Quantum Physics · Physics 2026-01-21 Sijie Cheng , Narayanan Rengaswamy

While the concept of entanglement purification protocols (EPPs) is straightforward, the integration of EPPs in network architectures requires careful performance evaluations and optimizations that take into account realistic conditions and…

Quantum Physics · Physics 2025-07-14 Allen Zang , Xin-An Chen , Eric Chitambar , Martin Suchara , Tian Zhong

We present the convergence study of a recurrence entanglement purification protocol using arbitrary two-qubit initial states. The protocol is based on a rank two projector in the Bell basis which serves as a two-qubit operation replacing…

Quantum Physics · Physics 2016-11-23 Juan Mauricio Torres , József Zsolt Bernád

The past decade has seen tremendous progress in experimentally realizing the building blocks of quantum repeaters. Repeater architectures with multiplexed quantum memories have been proposed to increase entanglement distribution rates, but…

Quantum Physics · Physics 2022-10-26 Yuan Lee , Eric Bersin , Axel Dahlberg , Stephanie Wehner , Dirk Englund

Quantum switches are envisioned to be an integral component of future entanglement distribution networks. They can provide high quality entanglement distribution service to end-users by performing quantum operations such as entanglement…

Quantum Physics · Physics 2022-12-06 Nitish K. Panigrahy , Thirupathaiah Vasantam , Don Towsley , Leandros Tassiulas

Quantum data-center networks must distribute entanglement between QPUs over paths whose length grows with system scale, but each entanglement-swapping step reduces the quality of the raw end-to-end state. Topology, multiplexing, and…

We introduce a quantity called the coherence of purification which can be a measure of total quantumness for a single system. We prove that coherence of purification is always more than the coherence of the system. For a pure state, the…

Quantum Physics · Physics 2019-07-31 Arun Kumar Pati , Long-Mei Yang , Chiranjib Mukhopadhyay , Shao-Ming Fei , Zhi-Xi Wang

In quantum networks multipath entanglement purification (MEP) between a pair of source-destination nodes can substantially strengthen their entanglement connection. An efficient MEP strategy can therefore increase the size of the network…

Quantum Physics · Physics 2024-08-28 Md Sohel Mondal , Siddhartha Santra

Entanglement and coherence are fundamental properties of quantum systems, promising to power near future quantum technologies, such as quantum computation, quantum communication and quantum metrology. Yet, their quantification, rather than…

Entanglement between two quantum systems is a resource in quantum information, but dissipation usually destroys it. In this article we consider two qubits without direct interaction and we show that, even in cases where the open system…

Quantum Physics · Physics 2015-06-26 Alberto Barchielli , Matteo Gregoratti

We introduce a figure of merit for a quantum memory which measures the preservation of entanglement between a qubit stored in and retrieved from the memory and an auxiliary qubit. We consider a general quantum memory system consisting of a…

Quantum Physics · Physics 2009-11-13 K. Surmacz , J. Nunn , F. C. Waldermann , Z. Wang , I. Walmsley , D. Jaksch