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Detection of entanglement in quantum networks consisting of many parties is one of the important steps towards building quantum communication and computation networks. We consider a scenario where the measurement devices used for this…

Quantum Physics · Physics 2017-05-03 Ivan Šupić , Paul Skrzypczyk , Daniel Cavalcanti

Entanglement depth quantifies how many qubits share genuine multipartite entanglement, but certification typically relies on tailored witnesses or full tomography, both of which scale poorly with system size. We recast entanglement-depth…

Quantum Physics · Physics 2025-12-16 Marcin Płodzień

We consider pure quantum states of N qubits and study the genuine N-qubit entanglement that is shared among all the N qubits. We introduce an information-theoretic measure of genuine N-qubit entanglement based on bipartite partitions. When…

Quantum Physics · Physics 2007-05-23 Jian-Ming Cai , Zheng-Wei Zhou , Xing-Xiang Zhou , Guang-Can Guo

Entanglement, while being critical in many quantum applications, is difficult to characterize experimentally. While entanglement witnesses based on the fidelity to the target entangled state are efficient detectors of entanglement, they in…

Quantum Physics · Physics 2020-01-29 Won Kyu Calvin Sun , Alexandre Cooper , Paola Cappellaro

Entangled measurement is a crucial tool in quantum technology. We propose a new entanglement measure of multi-mode detection, which estimates the amount of entanglement that can be created in a measurement. To illustrate the proposed…

Mutually unbiased bases, mutually unbiased measurements and general symmetric informationally complete measurements are three related concepts in quantum information theory. We investigate multipartite systems using these notions and…

Quantum Physics · Physics 2018-02-27 Lu Liu , Ting Gao , Fengli Yan

We generate and characterise entangled states of a register of 20 individually controlled qubits, where each qubit is encoded into the electronic state of a trapped atomic ion. Entanglement is generated amongst the qubits during the…

Quantum benchmarks are routinely used to validate the experimental demonstration of quantum information protocols. Many relevant protocols, however, involve an infinite set of input states, of which only a finite subset can be used to test…

Quantum Physics · Physics 2021-09-28 Ge Bai , Giulio Chiribella

Many experiments in quantum information aim at creating multi-partite entangled states. Quantifying the amount of entanglement that was actually generated can, in principle, be accomplished using full-state tomography. This method requires…

Quantum Physics · Physics 2015-05-13 Harald Wunderlich , Martin B. Plenio

A complete, non-demolition procedure is established for measuring multi-qubit entangled states, such as the Bell-states and the GHZ-states, which is essential in certain processes of quantum communication, computation, and teleportation. No…

Quantum Physics · Physics 2016-09-08 Ulf Larsen

Assessing the quality of an ensemble of noisy entangled states is a central task in quantum information processing. Usually this is done by measuring and hence destroying multiple copies, from which state tomography or fidelity estimation…

Quantum Physics · Physics 2023-02-14 Ferran Riera-Sàbat , Jorge Miguel-Ramiro , Wolfgang Dür

We address the question of whether or not global entanglement of a quantum state can be inferred from local properties. Specifically, we are interested in genuinely multiparticle entangled states whose two-body marginals are all separable,…

Quantum Physics · Physics 2018-12-05 Marius Paraschiv , Nikolai Miklin , Tobias Moroder , Otfried Gühne

Important properties of a quantum system are not directly measurable, but they can be disclosed by how fast the system changes under controlled perturbations. In particular, asymmetry and entanglement can be verified by reconstructing the…

Entanglement plays an indispensable role in numerous quantum information and quantum computation tasks, underscoring the need for efficiently verifying entangled states. In recent years, quantum state verification has received increasing…

Quantum Physics · Physics 2025-12-15 Lan Zhang , Yinfei Li , Ye-Chao Liu , Jiangwei Shang

Quantum entanglement is a key resource in quantum computing and quantum information processing tasks. However, its quantification remains a major challenge since it cannot be directly extracted from physical observables. To address this…

Quantum Physics · Physics 2025-12-29 Shruti Aggarwal , Trasha Gupta , R. K. Agrawal , S. Indu

Quantum entanglement is the key resource for quantum information processing. Device-independent certification of entangled states is a long standing open question, which arouses the concept of self-testing. The central aim of self-testing…

First, we show how the quantum circuits for generating and measuring multi-party entanglement of qubits can be translated to continuous quantum variables. We derive sufficient inseparability criteria for $N$-party continuous-variable states…

Quantum Physics · Physics 2007-05-23 Peter van Loock , Samuel L. Braunstein

We introduce an inductive $n$-qubit pure-state estimation method. This is based on projective measurements on states of $2n+1$ separable bases or $2$ entangled bases plus the computational basis. Thus, the total number of measurement bases…

Quantum Physics · Physics 2022-05-17 L. Pereira , L. Zambrano , A. Delgado

Multipartite entanglement is a crucial resource for a wide range of quantum information processing tasks, including quantum metrology, quantum computing, and quantum communication. The verification of multipartite entanglement, along with…

Quantum Physics · Physics 2024-12-24 Kai Wu , Zhihua Chen , Zhen-Peng Xu , Zhihao Ma , Shao-Ming Fei

Techniques developed for device-independent characterizations allow one to certify certain physical properties of quantum systems without assuming any knowledge of their internal workings. Such a certification, however, often relies on the…

Quantum Physics · Physics 2019-07-03 Pei-Sheng Lin , Jui-Chen Hung , Ching-Hsu Chen , Yeong-Cherng Liang