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Quantum entanglement is a key resource for quantum technologies, yet its efficient and high-fidelity generation remains a challenge due to the complexity of quantum dynamics. This paper presents a quantum optimal control framework to…

Quantum Physics · Physics 2025-07-15 Nahid Binandeh Dehaghani , A. Pedro Aguiar , Rafal Wisniewski

In device-independent quantum information processing Bell inequalities are not only used as detectors of nonlocality, but also as certificates of relevant quantum properties. In order for these certificates to work, one very often needs…

Quantum Physics · Physics 2019-11-06 Remigiusz Augusiak , Alexia Salavrakos , Jordi Tura , Antonio Acín

The nature of quantum correlations in strongly correlated systems has been a subject of intense research. In particular, it has been realized that entanglement and quantum discord are present at quantum phase transitions and able to…

Quantum Physics · Physics 2014-01-03 Thiago R. de Oliveira , A. Saguia , M. S. Sarandy

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.…

Quantum correlations described by quantum discord and one-way quantum deficit can contain ordinary regions with {\em constant} (i.e., universal) optimal measurement angle $0$ or $\pi/2$ with respect to the $z$-axis and regions with a {\em…

Quantum Physics · Physics 2019-04-05 Ekaterina V. Moreva , Marco Gramegna , Mikhail A. Yurischev

We have recently shown that for the special case of a bipartite system with binary inputs and outputs there exist equalities in local theories which are violated by quantum theory. The amount of white noise tolerated by these equalities are…

Quantum Physics · Physics 2008-10-16 Hossein Movahhedian

The existence of contextuality in quantum mechanics is a fundamental departure from the classical description of the world. Currently, the quest to identify scenarios which cannot be more contextual than quantum theory is at the forefront…

Quantum Physics · Physics 2019-08-14 Dileep Singh , Jaskaran Singh , Kavita Dorai , Arvind

Quantification of quantum entanglement plays a crucial role in the study of quantum information tasks. We present analytical lower bounds for both concurrence and 2-concurrence based on the correlation matrices of bipartite quantum states.…

Quantum Physics · Physics 2025-03-21 Zhi-Bo Chen , Shao-Ming Fei

Enhancing the quantum correlations in realistic quantum systems interacting with the environment of finite temperature is an important subject in quantum information processing. In this paper, we use weak measurement and measurement…

Quantum Physics · Physics 2014-06-25 Nasibollah Doustimotlagh , Shuhao Wang , Chenglong You , Gui-Lu Long

Deviations from classical physics when distant quantum systems become correlated are interesting both fundamentally and operationally. There exist situations where the correlations enable collaborative tasks that are impossible within the…

Quantum Physics · Physics 2019-05-08 Farid Shahandeh , Austin P. Lund , Timothy C. Ralph

We consider the problem of quantum multi-parameter estimation with experimental constraints and formulate the solution in terms of a convex optimization. Specifically, we outline an efficient method to identify the optimal strategy for…

Quantum Physics · Physics 2013-05-29 Kevin C. Young , Mohan Sarovar , Robert Kosut , K. Birgitta Whaley

Recently, the fast development of quantum technologies led to the need for tools allowing the characterization of quantum resources. In particular, the ability to estimate non-classical aspects, e.g. entanglement and quantum discord, in…

We investigate how much information about a quantum system can be simultaneously communicated to independent observers, by establishing quantitative limits to bipartite quantum correlations in many-body systems. As recently reported in…

Quantum Physics · Physics 2024-02-09 Davide Girolami , Michele Minervini

We consider a monogamy inequality of quantum discord in a pure tripartite state and show that it is equivalent to an inequality between quantum mutual information and entanglement of formation of two parties. Since this inequality does not…

Quantum Physics · Physics 2013-02-13 Xi-Jun Ren , Heng Fan

We investigate one-way communication scenarios where Bob manipulating on his parts can transfer some sub-system to the environment. We define reduced versions of quantum communication rates and further, prove new upper bounds on one-way…

Quantum Physics · Physics 2013-05-29 Marcin L. Nowakowski , Pawel Horodecki

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.…

The quantum fisher information and quantum correlation parameters are employed to study the application of non-classical light to the problem of parameter estimation. It is shown that the optimal measurement sensitivity of a quantum state…

Quantum Physics · Physics 2015-01-09 Jaspreet Sahota , Nicolás Quesada

The characterization of quantum information quantifiers has attracted a considerable attention of the scientific community, since they are a useful tool to verify the presence of quantum correlations in a quantum system. In this context, in…

Quantum Physics · Physics 2017-03-20 Clebson Cruz

When a collection of distant observers share an entangled quantum state, the statistical correlations among their measurements may violate a many-body Bell inequality, demonstrating a non-local behavior. Focusing on the Ising model in a…

Strongly Correlated Electrons · Physics 2019-10-25 Angelo Piga , Albert Aloy , Maciej Lewenstein , Irénée Frérot

We theoretically and experimentally investigate conditional enhancement of overall coherence of quantum states by probabilistic quantum operations that apply to the input state a quantum filter diagonal in the basis of incoherent states. We…

Quantum Physics · Physics 2021-08-03 Robert Stárek , Michal Mičuda , Michal Kolář , Radim Filip , Jaromír Fiurášek