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Chen (quant-ph/0611126) has recently claimed ``exponential violation of local realism by separable states", in the sense that multi-partite separable quantum states are supposed to give rise to correlations and fluctuations that violate a…

Quantum Physics · Physics 2007-05-23 M. Seevinck

We investigate the steerability of two-qubit Bell-diagonal states under projective measurements by the steering party. In the simplest nontrivial scenario of two projective measurements, we solve this problem completely by virtue of the…

Quantum Physics · Physics 2016-02-26 Quan Quan , Huangjun Zhu , Si-Yuan Liu , Shao-Ming Fei , Heng Fan , Wen-Li Yang

In a pair of correlated quantum systems a measurement in one corresponds to a change in the state of the other. In the process, information is lost. Measurement along which set of projectors would accompany minimum loss in information…

Quantum Physics · Physics 2022-05-19 Chitradeep Gupta

It is often said that measuring a system's position must disturb the complementary property, momentum, by some minimum amount due to the Heisenberg uncertainty principle. Using a "weak-measurement", this disturbance can be reduced. One…

Quantum Physics · Physics 2018-11-26 G. S. Thekkadath , F. Hufnagel , J. S. Lundeen

In past work, the concept of connectors was introduced: directed tensors with the property that any contraction thereof defines a multipartite quantum Bell inequality, i.e., a linear restriction on measurement probabilities that holds in…

Quantum Physics · Physics 2025-03-07 Paolo Abiuso , Julian Fischer , Miguel Navascués

It is not generally known, that the inequality that Bell derived using three random variables must be identically satisfied by any three corresponding data sets of plus and minus 1s that are writable on paper.This surprising fact is not…

Quantum Physics · Physics 2023-01-10 Louis Sica

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

We investigate evolution of quantum correlations in ensembles of two-qubit nuclear spin systems via nuclear magnetic resonance techniques. We use discord as a measure of quantum correlations and the Werner state as an explicit example. We…

Quantum Physics · Physics 2012-10-31 Hemant Katiyar , Soumya Singha Roy , T. S. Mahesh , Apoorva Patel

The quantum measurement procedure based on the Lorentz transformation formalism and weak perturbation of the system is considered. In the simple case of a single-qubit it turns out that one can perform 4-dimension pseudo-rotation along with…

Quantum Physics · Physics 2019-06-18 Yu. I. Bogdanova , N. A. Bogdanova , B. I. Bantysh , Yu. A. Kuznetsov

Entangled pure-states, Werner-states and generalized mixed-states of any structure, spanning a 2x2 Hilbert space are created by a novel high-brilliance universal source of polarization-entangled photon pairs. The violation of a Bell…

Quantum Physics · Physics 2007-05-23 M. Barbieri , F. De Martini , G. Di Nepi , P. Mataloni

Left on its own, a quantum state evolves deterministically under the Schr\"odinger Equation, forming superpositions. Upon measurement, however, a stochastic process governed by the Born rule collapses it to a single outcome. This dual…

Quantum Physics · Physics 2026-01-01 Anderson A. Tomaz , Rafael S. Mattos , Mario Barbatti

We employ the technique of weak measurement in order to enable preservation of teleportation fidelity for two-qubit noisy channels. We consider one or both qubits of a maximally entangled state to undergo amplitude damping, and show that…

Quantum Physics · Physics 2013-11-01 T. Pramanik , A. S. Majumdar

Steering, a quantum property stronger than entanglement but weaker than non-locality in the quantum correlation hierarchy, is a key resource for one-sided device-independent quantum key distribution applications, in which only one of the…

It has been suggested that there may exist quantum correlations that go beyond entanglement. The existence of such correlations can be revealed by quantum discord, but not by the conventional measure of entanglement. We argue that a state…

Quantum Physics · Physics 2016-09-30 Pankaj Agrawal , Sk Sazim , Indranil Chakrabarty , Arun K. Pati

We investigate the relationship between projective measurements and positive operator-valued measures (POVMs) in the task of quantum steering. A longstanding open problem in the field has been whether POVMs are more powerful than projective…

Quantum Physics · Physics 2025-01-06 Yujie Zhang , Eric Chitambar

The concept of self-testing (or rigidity) refers to the fact that for certain Bell inequalities the maximal violation can be achieved in an essentially unique manner. In this work we present a family of Bell inequalities which are maximally…

Quantum Physics · Physics 2020-09-22 Jędrzej Kaniewski

Composite quantum systems can be in generic states characterized not only by entanglement, but also by more general quantum correlations. The interplay between these two signatures of nonclassicality is still not completely understood. In…

Quantum Physics · Physics 2011-11-17 Davide Girolami , Gerardo Adesso

Quantum correlation often refers to correlations exhibited by two or more local subsystems under a suitable measurement. These correlations are beyond the framework of classical statistics and the associated classical probability…

Quantum Physics · Physics 2022-11-09 Biveen Shajilal , Elanor Huntington , Ping Koy Lam , Syed Assad

The distance between a quantum state and its closest state not having a certain property has been used to quantify the amount of correlations corresponding to that property. This approach allows a unified view of the various kinds of…

It is known that a reliable geometric quantifier of discord-like correlations can be built by employing the so-called trace distance. This is used to measure how far the state under investigation is from the closest "classical-quantum" one.…

Quantum Physics · Physics 2014-01-24 F. Ciccarello , T. Tufarelli , V. Giovannetti