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.

Local quantum uncertainty for a class of two-qubit X states and quantum correlations dynamics under decoherence

2017 ◽  
Vol 15 (01) ◽  
pp. 1750001 ◽  
Author(s):  
L. Jebli ◽  
B. Benzimoune ◽  
M. Daoud
Keyword(s):  
Quantum Discord ◽  
Quantum Correlations ◽  
Von Neumann Entropy ◽  
Trace Distance ◽  
Von Neumann ◽  
Quantum Uncertainty ◽  
Local Quantum Uncertainty ◽  
Local Quantum ◽  
Two Parameters ◽  
Qubit States

A special emphasis is devoted to the concept of local quantum uncertainty as an indicator of quantum correlations. We study quantum discord for a class of two-qubit states parametrized by two parameters. Quantum discord based on local quantum uncertainty, von Neumann entropy and trace distance (Schatten 1-norm) are explicitly derived and compared. The behavior of quantum correlations, quantified via local quantum uncertainty, under decoherence effects is investigated. We show that the discordlike local quantum uncertainty exhibits the possibility of freezing behavior during its evolution.

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.

Thermal quantum correlations in the two-qubit Heisenberg XYZ spin chain with Dzyaloshinskii–Moriya interaction

2021 ◽  
pp. 2150074
Author(s):  
Youssef Khedif ◽  
Mohammed Daoud
Keyword(s):  
Quantum Correlations ◽  
Thermal Fluctuations ◽  
Quantum Nonlocality ◽  
Chain Model ◽  
Trace Distance ◽  
Heisenberg Spin ◽  
Logarithmic Negativity ◽  
Qubit System ◽  
Classical Correlations ◽  
Moriya Interaction

We investigate the quantum correlations of a two-qubit XYZ Heisenberg spin-1/2 chain model with Dzyaloshinskii–Moriya interaction. The two-qubit system is considered in thermal equilibrium. The variations of logarithmic negativity, uncertainty-induced quantum nonlocality (UIN) and trace distance discord, versus the parameters characterizing the system, are analyzed. The results show that the UIN measure captures quantum correlations that cannot be revealed by entanglement and trace discord. We also show that the Dzyaloshinskii–Moriya interaction enhances the non-classical correlations between the spins and can weaken the undesirable destructive effects of thermal fluctuations. In addition, an entangled–unentangled phase transition can be detected from the behavior of logarithmic negativity.

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.

Quantum correlations and coherence dynamics in qutrit–qutrit systems under mixed classical environmental noises

2017 ◽  
Vol 15 (06) ◽  
pp. 1750047 ◽  
Author(s):  
Tsamouo Tsokeng Arthur ◽  
Tchoffo Martin ◽  
Lukong Cornelius Fai
Keyword(s):  
Sudden Death ◽  
Quantum Discord ◽  
Quantum Correlations ◽  
Collective Effects ◽  
Markovian Environment ◽  
Dynamic Noise ◽  
Long Time ◽  
Noise Models ◽  
Markovian Regime ◽  
Static Noise

We investigate the dynamics of entanglement, quantum discord (QD) and state coherence in a bipartite and noninteracting spin-qutrits system under mixed classical noises. Specifically, the collective effects of static noise (SN) and random telegraphic noise (RTN) each being coupled with a marginal system, are analyzed. While the static noise models a non-Markovian environment, the dynamic noise can model both a Markovian or a non-Markovian environment, and both dynamics are studied. We show that quantum correlations and coherence may survive the noise degrading effects at sufficiently long time when the Markovian regime of the RTN is considered. Meanwhile, the opposite is found in the non-Markovian regime, wherein the nonmonotonic dynamics of quantum features avoid sudden death phenomena. However, the static noise is more fatal to the survival of quantum correlations and quantum state coherence as compared to the RTN.

scholarly journals Experimental estimation of quantum discord for a polarization qubit and the use of fidelity to assess quantum correlations

2013 ◽  
Vol 87 (5) ◽  
Author(s):  
Claudia Benedetti ◽  
Alexander P. Shurupov ◽  
Matteo G. A. Paris ◽  
Giorgio Brida ◽  
Marco Genovese
Keyword(s):  
Quantum Discord ◽  
Quantum Correlations ◽  
Experimental Estimation

Dynamics of Interacting Classical and Quantum Systems

2011 ◽  
Vol 18 (04) ◽  
pp. 339-351 ◽  
Author(s):  
Dariusz Chruściński ◽  
Andrzej Kossakowski ◽  
Giuseppe Marmo ◽  
E. C. G. Sudarshan
Keyword(s):  
Characteristic Feature ◽  
Quantum Dynamics ◽  
Quantum Discord ◽  
Main Idea ◽  
Quantum Correlations ◽  
Quantum Systems ◽  
Quantum States ◽  
Algebra Of Observables ◽  
Classical Quantum ◽  
True Quantum

We analyze the dynamics of coupled classical and quantum systems. The main idea is to treat both systems as true quantum ones and impose a family of superselection rules which imply that the corresponding algebra of observables of one subsystem is commutative and hence may be treated as a classical one. Equivalently, one may impose a special symmetry which restricts the algebra of observables to the 'classical' subalgebra. The characteristic feature of classical-quantum dynamics is that it leaves invariant a subspace of classical-quantum states, that is, it does not create quantum correlations as measured by the quantum discord.

Local quantum uncertainty and trace distance discord dynamics for two-qubit X states embedded in non-Markovian environment

2018 ◽  
Vol 32 (20) ◽  
pp. 1850218 ◽  
Author(s):  
Youssef Khedif ◽  
Mohammed Daoud
Keyword(s):  
Quantum Correlations ◽  
Trace Distance ◽  
Markovian Environment ◽  
Quantum Uncertainty ◽  
Local Quantum Uncertainty ◽  
Local Quantum ◽  
Limiting Case ◽  
Analytical Expressions ◽  
Qubit States ◽  
Markovian Regime

We investigate the behavior of quantum correlations in some specific Werner-like two-qubit states, where the qubit interacts individually with non-Markovian environment. We employ the local quantum uncertainty and trace distance discord to quantify the amount of quantum correlations between the evolved qubits and the corresponding analytical expressions are derived. For specific values of the parameters characterizing the whole system, the dynamics of quantum correlations exhibits collapse and revival phenomena. The influence of the non-Markovianity is also investigated to analyze the monotonic decay of quantum correlations in the limiting case of Markovian regime. Furthermore, we show that trace distance discord captures quantum correlations that cannot be revealed by local quantum uncertainty in some particular situations.

Improvement of quantum correlations by repetitive quantum error correction

2019 ◽  
Vol 17 (05) ◽  
pp. 1950044
Author(s):  
A. El Allati ◽  
H. Amellal ◽  
A. Meslouhi
Keyword(s):  
Error Correction ◽  
Quantum Correlation ◽  
Coherent States ◽  
Quantum Discord ◽  
Error Correcting Code ◽  
Quantum Correlations ◽  
Quantum Error Correction ◽  
Optical Field ◽  
Quantum Error ◽  
Entangled Coherent States

A quantum error-correcting code is established in entangled coherent states (CSs) with Markovian and non-Markovian environments. However, the dynamic behavior of these optical states is discussed in terms of quantum correlation measurements, entanglement and discord. By using the correcting codes, these correlations can be as robust as possible against environmental effects. As the number of redundant CSs increases due to the repetitive error correction, the probabilities of success also increase significantly. Based on different optical field parameters, the discord can withstand more than an entanglement. Furthermore, the behavior of quantum discord under decoherence may exhibit sudden death and sudden birth phenomena as functions of dimensionless parameters.

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