scholarly journals Geometric measure of quantum discord and total quantum correlations in anN-partite quantum state

2012 ◽  
Vol 45 (34) ◽  
pp. 345301 ◽  
Author(s):  
Ali Saif M Hassan ◽  
Pramod S Joag
Keyword(s):  
Quantum State ◽  
Quantum Discord ◽  
Quantum Correlations ◽  
Geometric Measure

QUANTUM CORRELATIONS IN THE "q-DEFORMED" WERNER STATE

2013 ◽  
Vol 11 (02) ◽  
pp. 1350018 ◽  
Author(s):  
BO LIU ◽  
KANG XUE ◽  
GANGCHENG WANG ◽  
CHUNFANG SUN ◽  
LIDAN GOU ◽  
...  
Keyword(s):  
Quantum Discord ◽  
Singlet State ◽  
Great Influence ◽  
Quantum Correlations ◽  
Werner State ◽  
Single Loop ◽  
Geometric Measure ◽  
Topological Parameter ◽  
Spin Singlet ◽  
Two Parameters

We investigate quantum discord of the "q-deformed" Werner state via Yang–Baxterization approach. There are two parameters q and u in this "q-deformed" Werner state. The parameter u, which plays an important role in some typical models, is related to the probability of the "q-deformed" two-qubit spin singlet state in this study. The "q-deformed" parameter q is related to the single loop through d = q + q-1. When topological parameter d approaches 2 (i.e. q → 1), the "q-deformed" Werner state degenerates into the well-known Werner state. The results show that topological parameter d has great influence on quantum correlations of the "q-deformed" Werner state. When we fix the parameter u, the quantum correlations decrease with increasing the single loop d. When d approaches +∞ (i.e. q → 0+ or +∞), quantum discord, geometric measure of quantum discord and entanglement all tend to 0. While d approaches 2 (i.e. q → 1), all of them just have the same results with the Werner state.

Oblique discord

2017 ◽  
Vol 31 (02) ◽  
pp. 1650256
Author(s):  
Jianwei Xu
Keyword(s):  
Quantum Correlation ◽  
Quantum Discord ◽  
Orthonormal Basis ◽  
Quantum Correlations ◽  
Information Theoretic ◽  
Separable States ◽  
Geometric Measure ◽  
Definition Of

Discord and entanglement characterize two kinds of quantum correlations, and discord captures more correlation than entanglement in the sense that even separable states may have nonzero discord. In this paper, we propose a new kind of quantum correlation that we call as oblique discord. A zero-discord state corresponds to an orthonormal basis, while a zero-oblique-discord state corresponds to a basis which is not necessarily orthogonal. Under this definition, the set of zero-discord states is properly contained inside the set of zero-oblique-discord states, and the set of zero-oblique-discord states is properly contained inside the set of separable states. We give a characterization of zero-oblique-discord states via quantum mapping, provide a geometric measure for oblique discord, and raise a conjecture, which if it holds, then we can define an information-theoretic measure for oblique discord. Also, we point out that the definition of oblique discord can be properly extended to some different versions just as the case of quantum discord.

QUANTUM CORRELATIONS AT FINITE TEMPERATURE

2012 ◽  
Vol 10 (02) ◽  
pp. 1250027 ◽  
Author(s):  
LIANG QIU
Keyword(s):  
Sudden Death ◽  
Finite Temperature ◽  
Quantum Discord ◽  
Quantum Correlations ◽  
Entangled States ◽  
Dense Coding ◽  
Geometric Measure ◽  
Bell Nonlocality ◽  
Maximally Entangled States

We show that, under the influence of finite temperature reservoirs, for a board class of states, Bell nonlocality always endures sudden death. Furthermore, for two states evolved from two different maximally entangled states, the larger the concurrence and quantum discord, the better the resource for dense coding. However, the more usefulness of a state for teleportation could not be owed to the larger negativity and geometric measure of discord.

scholarly journals Quantum discord for investigating quantum correlations without entanglement in solids

2012 ◽  
Vol 86 (10) ◽  
Author(s):  
Xing Rong ◽  
Zixiang Wang ◽  
Fangzhou Jin ◽  
Jianpei Geng ◽  
Pengbo Feng ◽  
...  
Keyword(s):  
Quantum Discord ◽  
Quantum Correlations

Dynamics of quantum correlations in a qubit-qutrit spin system under random telegraph noise

2021 ◽  
Author(s):  
Fadwa Benabdallah ◽  
Hamid Arian Zad ◽  
Mohammed Daoud ◽  
Nerses S Ananikian
Keyword(s):  
High Temperatures ◽  
Quantum Discord ◽  
Quantum Correlations ◽  
Spin Model ◽  
Dimensionless Time ◽  
Random Telegraph Noise ◽  
Geometric Quantum Discord ◽  
Logarithmic Negativity ◽  
Telegraph Noise ◽  
Real Complex

Abstract We study the dimensionless time evolution of the logarithmic negativity and geometric quantum discord of a qubit-qutrit XXX spin model under the both Markovian and non-Markovian noise channels. We find that at a special temperature interval the quantum entanglement based on the logarithmic negativity reveals entanglement sudden deaths together with revivals. The revival phenomenon is due to the non-Markovianity resulting from the feedback effect of the environment. At high temperatures, the scenario of death and revival disappears. The geometric quantum discord evolves alternatively versus time elapsing with damped amplitudes until the system reaches steady state. It is demonstrated that the dynamics of entanglement negativity undergoes substantial changes by varying temperature, and it is much more fragile against the temperature rather than the geometric quantum discord. The real complex heterodinuclear [Ni(dpt (H2O)Cu(pba)]·2H2O [with pba =1,3-propylenebis(oxamato) and dpt = bis-(3-aminopropyl)amine] is an experimental representative of our considered bipartite qubit-qutrit system that may show remarkable entanglement deaths and revivals at relatively high temperatures and high magnetic field that is comparable with the strength of the exchange interaction J between Cu+2 and Ni+2 ions, i.e., kBT ≈ J and μBB ≈ J.

scholarly journals Study on Non-Commutativity Measure of Quantum Discord

Mathematics ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 543 ◽  
Author(s):  
Jin Liang ◽  
Chengwei Zhang
Keyword(s):  
Explicit Expression ◽  
Quantum Discord ◽  
Dynamic Models ◽  
Quantum Correlations ◽  
Trace Distance ◽  
Qualitative Representation

In this paper, we are concerned with the non-commutativity measure of quantum discord. We first present an explicit expression of the non-commutativity measure of quantum discord in the two-qubit case. Then we compare the geometric quantum discords for two dynamic models with their non-commutativity measure of quantum discords. Furthermore, we show that the results conducted by the non-commutativity measure of quantum discord are different from those conducted by both or one of the Hilbert-Schmidt distance discord and trace distance discord. These intrinsic differences indicate that the non-commutativity measure of quantum discord is incompatible with at least one of the well-known geometric quantum discords in the quantitative and qualitative representation of quantum correlations.

scholarly journals INTERPLAY BETWEEN QUANTUM PHASE TRANSITIONS AND THE BEHAVIOR OF QUANTUM CORRELATIONS AT FINITE TEMPERATURES

2012 ◽  
Vol 27 (01n03) ◽  
pp. 1345032 ◽  
Author(s):  
T. WERLANG ◽  
G. A. P. RIBEIRO ◽  
GUSTAVO RIGOLIN
Keyword(s):  
Phase Transitions ◽  
Critical Point ◽  
Thermodynamic Limit ◽  
Quantum Discord ◽  
Quantum Phase Transitions ◽  
Quantum Correlations ◽  
Infinite Chain ◽  
Quantum Phase ◽  
Absolute Zero ◽  
Zero Temperature

We review the main results and ideas showing that quantum correlations at finite temperatures (T), in particular quantum discord, are useful tools in characterizing quantum phase transitions (QPT) that only occur, in principle, at the unattainable absolute zero temperature. We first review some interesting results about the behavior of thermal quantum discord for small spin-1/2 chains and show that they already give us important hints of the infinite chain behavior. We then study in detail and in the thermodynamic limit (infinite chains) the thermal quantum correlations for the XXZ and XY models, where one can clearly appreciate that the behavior of thermal quantum discord at finite T is a useful tool to spotlight the critical point of a QPT.

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