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The Quantum Fisher Information (QFI) plays a crucial role in quantum information theory and in many practical applications such as quantum metrology. However, computing the QFI is generally a computationally demanding task. In this work we…

Quantum Physics · Physics 2021-06-25 M. Cerezo , Akira Sone , Jacob L. Beckey , Patrick J. Coles

Quantum Fisher information (QFI) and skew information (SI) plays a key role in the quantum resource theory. Understanding these measures in the physical system has practical significance in the state parameter estimation and quantum…

Quantum Physics · Physics 2021-11-17 R. Muthuganesan , V. K. Chandrasekar

We study the quantum Fisher information (QFI) and, thus, the multipartite entanglement structure of thermal pure states in the context of the Eigenstate Thermalization Hypothesis (ETH). In both the canonical ensemble and the ETH, the…

Statistical Mechanics · Physics 2020-02-04 Marlon Brenes , Silvia Pappalardi , John Goold , Alessandro Silva

Symmetry breaking underlies diverse phenomena from phase transitions in condensed matter to fundamental interactions in gauge theories. Despite many proposed indicators, a general quantification of symmetry breaking that is faithful,…

Statistical Mechanics · Physics 2025-09-10 Shion Yamashika , Shimpei Endo , Hiroyasu Tajima

Based on a geometrical argument introduced by Zukowski, a new multisetting Bell inequality is derived, for the scenario in which many parties make measurements on two-level systems. This generalizes and unifies some previous results.…

Quantum Physics · Physics 2009-11-13 Koji Nagata , Wieslaw Laskowski , Tomasz Paterek

Bell inequalities have traditionally been used to demonstrate that quantum theory is nonlocal, in the sense that there exist correlations generated from composite quantum states that cannot be explained by means of local hidden variables.…

For a multipartite quantum state, the maximal violation of all Bell inequalities constitutes a measure of its nonlocality [Loubenets, J. Math. Phys. 53, 022201 (2012)]. In the present article, for the maximal violation of Bell inequalities…

Quantum Physics · Physics 2022-07-06 Elena R. Loubenets , Min Namkung

Quantum Fisher Information (QFI) is a measure quantifying the sensitivity of a quantum state with respect to changes in tuning parameters in quantum metrology, and defining quantum speed limits. We show that even if the quantum state is…

Quantum Physics · Physics 2025-07-23 Alexander Kruchkov

In the case of bipartite two qubits systems, we derive the analytical expression of bound of Bell operator for any given pure state. Our result not only manifest some properties of Bell inequality, for example which may be violated by any…

Quantum Physics · Physics 2011-02-02 Yang Xiang

In this paper, we study the ground state Quantum Fisher Information (QFI) in one-dimensional spin-1 models, as witness to Multipartite Entanglement. The models addressed are the Bilinear-Biquadratic model, the most general isotropic…

Using extensive numerical analysis of 20,000 randomly generated two-qubit states, we provide a quantitative analysis of the connection between entanglement measures and Maximized Quantum Fisher Information (MQFI). Our systematic study shows…

Quantum Physics · Physics 2025-10-03 Volkan Erol

In this paper, we focus on two different kinds of multipartite correlation, $k$-nonseparability and $k$-partite entanglement, both of which can describe the essential characteristics of multipartite entanglement. We propose effective…

Quantum Physics · Physics 2022-01-21 Yan Hong , Xianfei Qi , Ting Gao , Fengli Yan

It is well known that classical information can be cloned, but non-orthogonal quantum states cannot be cloned, and non-commuting quantum states cannot be broadcast. We conceive a scenario in which the object we want to broadcast is the…

Quantum Physics · Physics 2013-05-20 Xiao-Ming Lu , Zhe Sun , Xiaoguang Wang , Shunlong Luo , C. H. Oh

Quantum entanglement is a quantum mechanical phenomenon where the quantum state of a many-body system with many degrees of freedom cannot be described independently of the state of each body with a given degree of freedom, no matter how far…

For linear combinations of quantum product averages in an arbitrary bipartite state, we derive new quantum Bell-form and CHSH-form inequalities with the right-hand sides expressed in terms of a bipartite state. This allows us to specify in…

Quantum Physics · Physics 2011-01-04 Elena R. Loubenets

An information-theoretic temporal Bell inequality is formulated to contrast classical and quantum computations. Any classical algorithm satisfies the inequality, while quantum ones can violate it. Therefore, the violation of the inequality…

Quantum Physics · Physics 2007-05-23 Fumiaki Morikoshi

States that strongly violate Bell's inequalities are required in many quantum informational protocols as, for example, in cryptography, secret sharing and the reduction of communication complexity. We investigate families of such states…

Quantum metrology is a science about quantum measurements and it plays a key role in precision of quantum parameter estimation. Meanwhile, quantum coherence is an important quantum feature and quantum Fisher information (QFI) is an…

Quantum Physics · Physics 2025-10-30 Jun-Long Zhao , Li Yu , Ming Yang , Chui-Ping Yang

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

We provide a novel criterion for identifying quantum correlation, which allows us to find connections between Bell type inequalities, entanglement detection, and correlation. We utilize the criterion to construct witness operators that can…

Quantum Physics · Physics 2007-05-23 Che-Ming Li , Li-Yi Hsu , Wei-Yang Lin , Yueh-Nan Chen , Der-San Chuu , Tobias Brandes
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