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We introduce and analyze an active steering protocol designed to target multipartite entangled states. The protocol involves multiple qubits subjected to weak Bell pair measurements with active feedback, where the feedback operations are…

Quantum Physics · Physics 2025-06-09 Samuel Morales , Silvia Pappalardi , Reinhold Egger

The aim of this thesis is to investigate quantum entanglement and quantum nonlocality of bipartite finite-dimensional systems (bipartite qudits). Entanglement is one of the most fascinating non-classical features of quantum theory, and…

Quantum Physics · Physics 2009-07-09 Christoph Spengler

With a probability of success of $95 \%$ we solve the separability problem for Bell diagonal qutrit states with positive partial transposition (PPT). The separability problem, i.e. distinguishing separable and entangled states, generally…

Quantum Physics · Physics 2022-09-22 Christopher Popp , Beatrix C. Hiesmayr

Entanglement is an important resource that allows quantum technologies to go beyond the classically possible. There are many ways quantum systems can be entangled, ranging from the archetypal two-qubit case to more exotic scenarios of…

Quantum Physics · Physics 2019-06-27 Nicolai Friis , Giuseppe Vitagliano , Mehul Malik , Marcus Huber

We show how to estimate a broad class of multipartite entanglement measures from Bell basis measurement data. In addition to lowering the experimental requirements relative to previously known methods of estimating these measures, our…

Quantum Physics · Physics 2023-07-12 Jacob L. Beckey , G. Pelegrí , Steph Foulds , Natalie J. Pearson

Measurements in the quantum domain can exceed classical notions. This concerns fundamental questions about the nature of the measurement process itself, as well as applications, such as their function as building blocks of quantum…

Quantum Physics · Physics 2023-02-02 Jan Sperling , Ilaria Gianani , Marco Barbieri , Elizabeth Agudelo

Bipartite quantum states with higher Schmidt numbers have been shown to outperform those with lower Schmidt numbers in various quantum information processing tasks, highlighting the operational advantage of entanglement dimensionality.…

Quantum Physics · Physics 2025-12-19 Saheli Mukherjee , Bivas Mallick , Arun Kumar Das , Amit Kundu , Pratik Ghosal

The efficient and reliable characterization of quantum states plays a vital role in most, if not all, quantum information processing tasks. In this work, we present a universally optimal protocol for verifying entangled states by employing…

Quantum Physics · Physics 2021-03-08 Ye-Chao Liu , Jiangwei Shang , Rui Han , Xiangdong Zhang

Violation of Bell inequalities is an essential requirement for many quantum information and communication protocols. In high-dimensional systems, Bell inequality tests face the challenge of implementing genuinely multi-outcome measurements,…

We consider the problem of demonstrating non-Bell-local correlations by performing local measurements in randomly chosen triads, i.e., three mutually unbiased bases, on a multipartite Greenberger-Horne-Zeilinger state. Our main interest…

Quantum Physics · Physics 2020-09-01 Shih-Xian Yang , Gelo Noel Tabia , Pei-Sheng Lin , Yeong-Cherng Liang

Starting from several copies of bipartite noisy entangled states, we design a global and optimal local measurement-based protocol in one- and two-dimensional lattices by which any two or more prefix sites can be connected via entanglement.…

Quantum Physics · Physics 2021-01-04 Ratul Banerjee , Srijon Ghosh , Shiladitya Mal , Aditi Sen De

We propose to detect quantum entanglement by a condition of local measurments. We find that this condition can detect efficiently the pure entangled states for both discrete and continuous variable systems. It does not depend on…

Quantum Physics · Physics 2015-05-30 Qing Xie , X. -X. Wu , X. -M. Ding , W. -L. Yang , R. -H. Yue , H. Fan

We present a device-independent protocol to test if a given black-box measurement device is entangled, that is, has entangled eigenstates. Our scheme involves three parties and is inspired by entanglement swapping; the test uses the…

Quantum Physics · Physics 2011-08-03 Rafael Rabelo , Melvyn Ho , Daniel Cavalcanti , Nicolas Brunner , Valerio Scarani

Unpredictability, or randomness, of the outcomes of measurements made on an entangled state can be certified provided that the statistics violate a Bell inequality. In the standard Bell scenario where each party performs a single…

Quantum Physics · Physics 2017-03-01 F. J. Curchod , M. Johansson , R. Augusiak , M. J. Hoban , P. Wittek , A. Acín

Characterizing large quantum systems with minimal assumptions is a central challenge in quantum information science. Self-testing provides the strongest form of certification by identifying the underlying quantum state solely from observed…

Quantum Physics · Physics 2026-05-15 Jinchang Liu , Elias X. Huber , Zhenyu Du , Xingjian Zhang , Xiongfeng Ma

Quantum entanglement is one of the most important resources in quantum information. In recent years, the research of quantum entanglement mainly focused on the increase in the number of entangled qubits or the high-dimensional entanglement…

We describe a protocol for cross-platform verification of quantum simulators and quantum computers. We show how to measure directly the overlap $\textrm{Tr}\left[\rho_1 \rho_2\right]$ and the purities $\textrm{Tr}\left[\rho^2_{1,2}\right]$,…

Quantum correlations in Bell and prepare-and-measure experiments are central resources for probing nonclassicality and enabling device-based quantum information protocols. In the absence of shared public randomness (i.e., without run-to-run…

Quantum Physics · Physics 2026-04-21 Liang-Liang Sun , Xiang Zhou , Chengjie Zhang , Zizhu Wang , Yong-Shun Song , Sixia Yu

We present here a classical optics device based on an imaging architecture as analogy of a quantum system where the violation of the Bell inequality can be evidenced. In our case, the two qbits entangled state needed to obtain non classical…

Quantum Physics · Physics 2009-04-22 M. Goldin , D. Francisco , S. Ledesma

Using the type-I SPDC process in BBO nonlinear crystal (NLC), we generate a polarization-entangled state near to the maximally-entangled Bell-state with high-visibility (high-brightness) $ 98.50 \pm 1.33 ~ \% $ ($ 87.71 \pm 4.45 ~ \% $) for…

Quantum Physics · Physics 2021-07-06 Ali Motazedifard , Seyed Ahmad Madani , N. S. Vayaghan