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One of the fundamental concepts of quantum information theory is that of entanglement purification; that is, the transformation of a partially entangled state into a smaller-dimensional, more completely entangled state. Of particular…

Quantum Physics · Physics 2008-02-03 Eric M. Rains

Collective measurements on large quantum systems together with a majority voting strategy can lead to a violation of the CHSH Bell inequality. In presence of many entangled pairs, this violation decreases quickly with the number of pairs,…

In this work, a theoretical generalization of Lloyd's quantum illumination to signal beams described by two entangled photon states is developed. It is shown that the new protocol offers a method to find the range of the target, reduces the…

Quantum Physics · Physics 2021-09-21 Ricardo Gallego Torromé , Nadya Ben Bekhti-Winkel , Peter Knott

We present a realistic purification scheme for pure non-maximally entangled states. In the scheme, Alice and Bob at two distant parties first start with two shared but less entangled photon pairs to produce a conditional four-photon GHZ…

Quantum Physics · Physics 2009-11-07 Zhi Zhao , Jian-Wei Pan , M. S. Zhan

A bipartite state which is secretly chosen from a finite set of known entangled pure states cannot be immediately useful in standard quantum information processing tasks. To effectively make use of the entanglement contained in this unknown…

Quantum Physics · Physics 2015-05-14 Yangjia Li , Runyao Duan , Mingsheng Ying

Nonlocality, manifested by the violation of Bell inequalities, indicates entanglement within a joint quantum system. A natural question is how much entanglement is required for a given nonlocal behavior. Here, we explore this question by…

Quantum Physics · Physics 2025-06-23 Yuwei Zhu , Xingjian Zhang , Xiongfeng Ma

Entangled photons have the remarkable ability to be more sensitive to signal and less sensitive to noise than classical light. Joint photons can sample an object collectively, resulting in faster phase accumulation and higher spatial…

Optics · Physics 2015-09-04 Chien-Hung Lu , Matthew Reichert , Xiaohang Sun , Jason W. Fleischer

Current photon entangling schemes require resources that grow with the photon number. We present a new approach that generates quantum entanglement between many photons, using only a single source of entangled photon pairs. The different…

Quantum Physics · Physics 2014-02-04 E. Megidish , T. Shacham , A. Halevy , L. Dovrat , H. S. Eisenberg

Quantum entanglement between paired photons is the foundation of optical quantum computing, quantum sensing, and quantum networks. Traditionally, quantum information science has focused on the particle nature of photons at the microscopic…

Quantum Physics · Physics 2024-10-03 Byoung S. Ham

Quantum thermodynamics and quantum entanglement represent two pivotal quantum resource theories with significant relevance in quantum information science. Despite their importance, the intricate relationship between these two theories is…

Quantum Physics · Physics 2025-03-26 Ray Ganardi , Piotr Masajada , Moein Naseri , Alexander Streltsov

A major outstanding problem for many quantum clock synchronization protocols is the hidden assumption of the availability of synchronized clocks within the protocol. In general, quantum operations between two parties do not have consistent…

Quantum Physics · Physics 2018-08-14 Ebubechukwu O. Ilo-Okeke , Louis Tessler , Jonathan P. Dowling , Tim Byrnes

Witnessing continuous-variable Bell nonlocality is a challenging endeavor, but Bell himself showed how one might demonstrate this nonlocality. Though Bell nearly showed a violation using the CHSH inequality with sign-binned…

Quantum Physics · Physics 2016-01-20 James Schneeloch , Samuel H. Knarr , Daniel J. Lum , John C. Howell

In this article, we investigate the purity dynamics of entangled 2 two-level atoms interacting with a single quantized electromagnetic field. We show that the purity of the qubit pairs depends on the initial state of the atomic system. It…

Quantum Physics · Physics 2008-03-20 Nasser Metwally

The distribution of entangled states of light over long distances is a major challenge in the field of quantum information. Optical losses, phase diffusion and mixing with thermal states lead to decoherence and destroy the non-classical…

We propose a new avenue towards distillation of quantum entanglement that is implemented by directly passing the entangled qubits through a mode-matched filter. This approach can be applied to a common class of entanglement impurities…

Quantum Physics · Physics 2015-05-30 Yu-Ping Huang , Prem Kumar

We show that the expectation value of squared correlations measured along random local directions is an identifier of quantum entanglement in pure states which can be directly experimentally assessed if two copies of the state were…

Quantum Physics · Physics 2015-11-18 Minh Cong Tran , Borivoje Dakic , Francois Arnault , Wieslaw Laskowski , Tomasz Paterek

Single-photon entanglement is a simple form of entanglement that exists between two spatial modes sharing a single photon. Despite its elementary form, it provides a resource as useful as polarization-entangled photons and it can be used…

Entanglement is a crucial quantum resource with broad applications in quantum information science. For harnessing entanglement in practice, it is a prerequisite to certify the entanglement of a given quantum state. However, the…

Quantum Physics · Physics 2023-10-11 Hyeon-Jin Kim , Ji-Hyeok Jung , Kyung-Jun Lee , Young-Sik Ra

The state of a two-particle system is called entangled when its quantum mechanical wave function cannot be factorized in two single-particle wave functions. Entanglement leads to the strongest counter-intuitive feature of quantum mechanics,…

Quantum Physics · Physics 2009-11-07 E. Altewischer , M. P. van Exter , J. P. Woerdman

Entangled quantum systems have properties that have fundamentally overthrown the classical worldview. Increasing the complexity of entangled states by expanding their dimensionality allows the implementation of novel fundamental tests of…

Quantum Physics · Physics 2014-05-01 Mario Krenn , Marcus Huber , Robert Fickler , Radek Lapkiewicz , Sven Ramelow , Anton Zeilinger