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Quantum networks with bipartite resources and shared randomness present the simplest infrastructure for implementing a future quantum internet. Here, we shall investigate which kinds of entanglement can or cannot be generated from this kind…

Quantum Physics · Physics 2025-03-13 Xiang Zhou , Zhen-Peng Xu , Liang-Liang Sun , Chunfeng Wu , Sixia Yu

Quantum networks distributed over distances greater than a few kilometers will be limited by the time required for information to propagate between nodes. We analyze protocols that are able to circumvent this bottleneck by employing…

The problem of state estimation for unobservable distribution systems is considered. A deep learning approach to Bayesian state estimation is proposed for real-time applications. The proposed technique consists of distribution learning of…

Machine Learning · Statistics 2019-02-26 Kursat Rasim Mestav , Jaime Luengo-Rozas , Lang Tong

A scheme is proposed by which two parties, Alice and Bob, can securely exchange real numbers. The scheme requires Alice and Bob to share entanglement and both to perform Bell-state measurements. With a qubit system two real numbers can each…

Quantum Physics · Physics 2007-05-23 Sung Soon Jang , Hai-Woong Lee

We present an alternative definition of quantum entanglement for bipartite system based on Bell inequality and operators' noncommutativity. A state is said to be entangled, if the maximum of CHSH expectation value $F_{\max}$ is obtain by…

Quantum Physics · Physics 2007-05-23 Li-Bin Fu , Jing-Ling Chen , Xian-Geng Zhao , Shi-Gang Chen

Distributed quantum information processing is a promising platform for scaling up quantum information processing, where small- and intermediate-scale quantum devices are connected by a network of quantum channels for communicating quantum…

Quantum Physics · Physics 2019-03-26 Hayata Yamasaki

We report on the first experimental reconstruction of an entanglement quasiprobability. In contrast to related techniques, the negativities in our distributions are a necessary and sufficient identifier of separability and entanglement and…

Quantum Physics · Physics 2019-02-08 J. Sperling , E. Meyer-Scott , S. Barkhofen , B. Brecht , C. Silberhorn

Bell-state projections serve as a fundamental basis for most quantum communication and computing protocols today. However, with current Bell-state measurement schemes based on linear optics, only two of four Bell states can be identified,…

Quantum Physics · Physics 2023-09-06 Matthias J. Bayerbach , Simone E. D'Aurelio , Peter van Loock , Stefanie Barz

We build a machine learning model to detect correlations in a three-qubit system using a neural network trained in an unsupervised manner on randomly generated states. The network is forced to recognize separable states, and correlated…

Quantum Physics · Physics 2024-08-20 Mateusz Krawczyk , Jarosław Pawłowski , Maciej M. Maśka , Katarzyna Roszak

Using the concept of non-degenerate Bell inequality, we show that quantum entanglement, the critical resource for various quantum information processing tasks, can be quantified for any unknown quantum states in a semi-device-independent…

Quantum entanglement is the essential resource for quantum communication and distributed information processing in a quantum network. However, the remote generation over a network suffers from inevitable transmission loss and other…

Quantum Physics · Physics 2025-12-09 Ye-Chao Liu , Otfried Gühne , Stefan Nimmrichter

Quantum properties, such as entanglement and coherence, are indispensable resources in various quantum information processing tasks. However, there still lacks an efficient and scalable way to detecting these useful features, especially for…

Quantum Physics · Physics 2021-11-03 Yiwei Chen , Yu Pan , Guofeng Zhang , Shuming Cheng

Nonlocal advantage of quantum coherence (NAQC) based on coherence complementarity relations is generally viewed as a stronger nonclassical correlation than Bell nonlocality. An arbitrary two-qubit state with NAQC must be an entangled state,…

Quantum Physics · Physics 2019-08-12 Zhi-Yong Ding , Huan Yang , Hao Yuan , Dong Wang , Jie Yang , Liu Ye

It is an established fact that entanglement is a resource. Sharing an entangled state leads to non-local correlations and to violations of Bell inequalities. Such non-local correlations illustrate the advantage of quantum resources over…

Quantum Physics · Physics 2015-10-07 P. Joshi , K. Horodecki , M. Horodecki , P. Horodecki , R. Horodecki , Ben Li , S. J. Szarek , T. Szarek

Bell measurements, entailing the projection onto one of the Bell states, play a key role in quantum information and communication, where the outcome of a variety of protocols crucially depends on the success probability of such…

Quantum Physics · Physics 2025-06-24 Luca Bianchi , Carlo Marconi , Jan Sperling , Davide Bacco

In the present study, we use cross-domain classification using quantum machine learning for quantum advantages to readdress the entanglement versus separability paradigm. The inherent structure of quantum states and its relation to a…

Quantum Physics · Physics 2025-04-09 Diksha Sharma , Vivek Balasaheb Sabale , Parvinder Singh , Atul Kumar

Dense coding is the seminal example of how entanglement can boost qubit communication, from sending one bit to sending two bits. This is made possible by projecting separate particles onto a maximally entangled basis. We investigate more…

In quantum information theory, the reliable and effective detection of entanglement is of paramount importance. However, given an unknown state, assessing its entanglement is a challenging task. To attack this problem, we investigate the…

Quantum Physics · Physics 2015-12-09 Jochen Szangolies , Hermann Kampermann , Dagmar Bruß

Quantum steering is observed when performing appropriate local measurements on an entangled state. Here we discuss the possibility of simulating classically this effect, using classical communication instead of entanglement. We show that…

Quantum Physics · Physics 2016-07-14 Ana Belén Sainz , Leandro Aolita , Nicolas Brunner , Rodrigo Gallego , Paul Skrzypczyk

Networking plays a ubiquitous role in quantum technology. It is an integral part of quantum communication and has significant potential for upscaling quantum computer technologies that are otherwise not scalable. Recently, it was realized…