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When a measurement is made on a system that is not in an eigenstate of the measured observable, it is often assumed that some conservation law has been violated. Discussions of the effect of measurements on conserved quantities often…

Quantum Physics · Physics 2021-08-27 Edward J. Gillis

Quantum discord as a measure of the quantum correlations cannot be easily computed for most of density operators. In this paper, we present a measure of the total quantum correlations that is operationally simple and can be computed…

Quantum Physics · Physics 2016-04-19 Javad Behdani , Seyed Javad Akhtarshenas , Mohsen Sarbishaei

Entanglement is known to be an essential resource for many quantum information processes. However, it is now known that some quantum features may be acheived with quantum discord, a generalized measure of quantum correlation. In this paper,…

Like entanglement, quantum discord quantifies the quantum correlations. Unlike entanglement, whose detection is extremely difficult, the quantum discord of an arbitrary bipartite state allows itself to be detected perfectly by a single…

Quantum Physics · Physics 2011-02-24 Sixia Yu , Chengjie Zhang , Qing Chen , C. H. Oh

Quantifying entanglement is a work in progress which is important for the active field of quantum information and computation. A measure of bipartite pure state entanglement is proposed here, named entanglement coherence, which is…

Quantum Physics · Physics 2022-02-15 Neha Pathania , Tabish Qureshi

Quantum measurements necessarily disturb the state of physical system. Once we perform a complete measurement, the system undergoes decoherence and loses its coherence. If there is no disturbance, the state retains all of its coherence. It…

Quantum Physics · Physics 2018-10-10 Gautam Sharma , Arun Kumar Pati

We analyze a family of measures of general quantum correlations for composite systems, defined in terms of the bipartite entanglement necessarily created between systems and apparatuses during local measurements. For every entanglement…

Quantum Physics · Physics 2012-04-04 Marco Piani , Gerardo Adesso

In this paper, we present the concept of the one-way unlocalizable quantum discord and investigate its properties. We provide a polygamy inequality for it in tripartite pure quantum system of arbitrary dimension. Several tradeoff relations…

Quantum Physics · Physics 2013-05-30 Zhengjun Xi , Heng Fan , Yongming Li

Quantum discord is a manifestation of quantum correlations due to non-commutativity rather than entanglement. Two measures of quantum discord by the amount of non-commutativity via the trace norm and the Hilbert-Schmidt norm respectively…

Quantum Physics · Physics 2016-05-03 Yu Guo

Entanglement, which is an essential characteristic of quantum mechanics, is the key element in potential practical quantum information and quantum communication systems. However, there are many open and fundamental questions (relating to…

Quantum Physics · Physics 2015-05-18 G. W. Ford , Yang Gao , R. F. O'Connell

An entanglement measure for a bipartite quantum system is a state functional that vanishes on separable states and that does not increase under separable (local) operations. It is well-known that for pure states, essentially all…

Quantum Physics · Physics 2025-08-22 Stefan Hollands , Ko Sanders

One-way quantum deficit and quantum discord are two important measures of quantum correlations. We revisit the relationship between them in two-qubit systems. We investigate the conditions that both one-way quantum deficit and quantum…

Quantum Physics · Physics 2016-01-12 Biao-Liang Ye , Shao-Ming Fei

Here, we show that partial transposition, which is initially introduced to study entanglement, can also inspire many results on quantum discord including: (I) a discord criterion of spectrum invariant under partial transposition, stating…

Quantum Physics · Physics 2023-05-17 Sun Liang-Liang , Zhou Xiang , Yu Sixia

We discuss a general notion of quantum correlations in fermionic or bosonic indistinguishable particles. Our approach is mainly based on the identification of the algebra of single-particle observables, which allows us to devise an…

Quantum Physics · Physics 2014-03-18 Fernando Iemini , Tiago Debarba , Reinaldo O. Vianna

Quantum discord is a measure of the quantumness of correlations. After reviewing its different versions and properties, we apply it to the questions of quantum information processing. First we show that changes in discord in the processed…

Quantum Physics · Physics 2015-03-17 Aharon Brodutch , Alexei Gilchrist , Daniel R. Terno , Christopher J. Wood

We calculate the quantum discord between two free modes of a scalar field which start in a maximally entangled state and then undergo a relative, constant acceleration. In a regime where there is no distillable entanglement due to the Unruh…

Quantum Physics · Physics 2013-05-29 Animesh Datta

Macroscopic behavior such as the lack of interference patterns has been attributed to "decoherence", a word with several possible definitions such as (1) the loss of off-diagonal density matrix elements, (2) the flow of information to the…

Quantum Physics · Physics 2015-05-30 Patrick J. Coles

Coherent interactions that generate negligible entanglement can still exhibit unique quantum behaviour. This observation has motivated a search beyond entanglement for a complete description of all quantum correlations. Quantum discord is a…

Complementary relationships exist regarding interference properties of particles such as pattern visibility, predictability and distinguishability. Additionally, relationships are known between information gain $G$ and measurement…

Quantum Physics · Physics 2024-09-04 Michael Steiner , Ronald Rendell

Quantum measurement is a class of quantum channels that sends quantum states to classical states. We set up resource theories of quantum coherence and quantum entanglement for quantum measurements and find relations between them. For this,…

Quantum Physics · Physics 2022-08-15 Ho-Joon Kim , Soojoon Lee