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We theoretically evaluate establishing remote entanglement between distinguishable matter qubits through interference and detection of two emitted photons. The fidelity of the entanglement operation is analyzed as a function of the temporal…

Quantum Physics · Physics 2016-12-02 A. M. Dyckovsky , S. Olmschenk

In state-of-the-art quantum key distribution (QKD) systems, the main limiting factor in increasing the key generation rate is the timing resolution in detecting photons. Here, we present and experimentally demonstrate a strategy to overcome…

Quantum Physics · Physics 2021-07-29 Johannes Pseiner , Lukas Achatz , Lukas Bulla , Martin Bohmann , Rupert Ursin

We propose a hybrid approach to the experimental assessment of the genuine quantum features of a general system consisting of microscopic and macroscopic parts. We infer entanglement by combining dichotomic measurements on a bidimensional…

Entanglement constitutes a key characteristic feature of quantum matter. Its detection, however, still faces major challenges. In this letter, we formulate a framework for probing entanglement based on machine learning techniques. The…

Quantum Physics · Physics 2021-08-18 Jun Yong Khoo , Markus Heyl

Quantifying unknown quantum entanglement experimentally is a difficult task, but also becomes more and more necessary because of the fast development of quantum engineering. Machine learning provides practical solutions to this fundamental…

Quantum Physics · Physics 2023-06-21 Xiaodie Lin , Zhenyu Chen , Zhaohui Wei

We review the status of Bell's inequalities in quantum information, stressing mainly the links with quantum key distribution and distillation of entanglement. We also prove that for all the eavesdropping attacks using one qubit, and for a…

Quantum Physics · Physics 2007-05-23 Antonio Acin , Nicolas Gisin , Lluis Masanes , Valerio Scarani

An efficiency-loophole-free quantum key distribution (QKD) scheme is proposed, which involves no hardware change but a modification in the data post-processing step. The scheme applies to a generic class of detection systems which allow…

Quantum Physics · Physics 2008-12-24 Xiongfeng Ma , Tobias Moroder , Norbert Lütkenhaus

We report on a complete free-space field implementation of a modified Ekert91 protocol for quantum key distribution using entangled photon pairs. For each photon pair we perform a random choice between key generation and a Bell inequality.…

Granting information privacy is of crucial importance in our society, notably in fiber communication networks. Quantum cryptography provides a unique means to establish, at remote locations, identical strings of genuine random bits, with a…

Entanglement -- the coherent correlations between parties in a joint quantum system -- is well-understood and quantifiable in the two-dimensional, two-party case. Higher (>2)-dimensional entangled systems hold promise in extending the…

Quantum Physics · Physics 2022-10-20 Alexandria J. Moore , Andrew M. Weiner

Coherent enhancement is a powerful mechanism for improving the sensitivity of a wide range of detectors, but its practical use is often limited by the difficulty of preparing the required quantum states. We show that this difficulty has a…

High Energy Physics - Phenomenology · Physics 2026-05-12 Zachary Bogorad , Roni Harnik

How can one prove that a given state is entangled? In this paper we review different methods that have been proposed for entanglement detection. We first explain the basic elements of entanglement theory for two or more particles and then…

Quantum Physics · Physics 2009-04-16 Otfried Gühne , Geza Toth

A quantum key distribution protocol based on entanglement swapping is proposed. Through choosing particles by twos from the sequence and performing Bell measurements, two communicators can detect eavesdropping and obtain the secure key.…

Quantum Physics · Physics 2007-05-23 Fei Gao , Fenzhuo Guo , Qiaoyan Wen , Fuchen Zhu

Entanglement-measurement attack is one of the most famous attacks against quantum cryptography. In quantum cryptography protocols, eavesdropping checking is an effective means to resist this attack. There are currently two commonly used…

Quantum Physics · Physics 2026-01-09 Zhaoxu Ji , Huanguo Zhang

Reliable verification of entanglement is a central requirement for quantum networks. This paper presents a practical verification approach based on violations of the Clauser-Horne-Shimony-Holt (CHSH) inequality. We derive tight mathematical…

Quantum Physics · Physics 2025-09-09 Xuan Du Trinh , Zhengyu Wu , Junlin Bai , Huan-Hsin Tseng , Nengkun Yu , Aruna Balasubramanian

The academic research into entanglement nicely illustrates the interplay between fundamental science and applications, and the need to foster both aspects to advance either one. For instance, the possibility to distribute entangled photons…

Quantum Physics · Physics 2016-05-25 Nicolas Gisin , Sébastien Tanzilli , Wolfgang Tittel

Quantum entanglement, a fundamental property ensuring security of key distribution and efficiency of quantum computing, is extremely sensitive to decoherence. Different procedures have been developed in order to recover entanglement after…

Quantum Physics · Physics 2008-04-23 Fabio Sciarrino , Eleonora Nagali , Francesco De Martini , Miroslav Gavenda , Radim Filip

In the recent decade, it has been discovered that QKD systems are extremely vulnerable to side-channel attacks. In particular, by exploiting the internal working knowledge of practical detectors, it is possible to bring them to an operating…

Quantum Physics · Physics 2015-02-02 Charles Ci Wen Lim , Nino Walenta , Matthieu Legre , Nicolas Gisin , Hugo Zbinden

We report the observation of entanglement between a single trapped atom and a single photon at a wavelength suitable for low-loss communication over large distances, thereby achieving a crucial step towards long range quantum networks. To…

Quantum Entanglement is widely regarded as one of the most prominent features of quantum mechanics and quantum information science. Although, photonic entanglement is routinely studied in many experiments nowadays, its signature has been…

Quantum Physics · Physics 2015-03-13 Robert Fickler , Mario Krenn , Radek Lapkiewicz , Sven Ramelow , Anton Zeilinger