Robustness of quantum discord to sudden death

2009 ◽  
Vol 80 (2) ◽  
Author(s):  
T. Werlang ◽  
S. Souza ◽  
F. F. Fanchini ◽  
C. J. Villas Boas
Keyword(s):  
Sudden Death ◽  
Quantum Discord

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 Local available quantum correlations for Bell Diagonal states and Markovian decoherence

2018 ◽  
Vol 64 (6) ◽  
pp. 662
Author(s):  
Hermann L Albrecht Q ◽  
Douglas F. Mundarain ◽  
Mario I. Caicedo S.
Keyword(s):  
Sudden Death ◽  
Quantum Discord ◽  
Quantum Correlations ◽  
Entanglement Sudden Death ◽  
Dissipative Dynamics ◽  
Phase Damping ◽  
Werner States ◽  
Kraus Operators

Local available quantum correlations (LAQCs), as dened by Mundarain et al. [19], are analytically determined for Bell Diagonal states. Using the Kraus operators formalism [10], we analyze the dissipative dynamics of 2-qubit LAQCs under Markovian decoherence. This is done for Werner states under the depolarizing [20] and phase damping channels [21]. Since Werner states are among those that exhibit the so called entanglement sudden death [27], the results are compared with the ones obtained for Quantum Discord [22], as analyzed by Werlang et al. [24], as well as for entanglement, i.e. Concurrence[7]. The LAQCs quantier, as Quantum Discord does, only vanishes asymptotically.

Nonlocal advantage of quantum coherence under relativistic frame

2018 ◽  
Vol 32 (31) ◽  
pp. 1850377 ◽  
Author(s):  
Long-Fei Wang ◽  
Ming-Ming Du ◽  
Wen-Yang Sun ◽  
Dong Wang ◽  
Liu Ye
Keyword(s):  
Sudden Death ◽  
Quantum Coherence ◽  
Quantum Discord ◽  
Thermal Noise ◽  
Unruh Effect ◽  
Qubit System ◽  
Bell Nonlocality ◽  
Better Than

In this paper, we investigate the influence of the Unruh effect on the achievement of the nonlocal advantage of quantum coherence for a two-qubit system under a relativistic frame. The results show that with the increase of acceleration, it is difficult to realize the nonlocal advantage of quantum coherence and when the acceleration exceeds a certain value, nonlocal advantage of quantum coherence cannot be realized. In addition, we explore the dynamics of Bell nonlocality, steering, quantum coherence, entanglement and quantum discord (QD) under Unruh thermal noise. It is shown that nonlocal advantage of quantum coherence, Bell nonlocality, steering and entanglement experience “sudden death” for a finite acceleration, while quantum coherence and QD vanish only in the limit of an infinite acceleration. We also find that not all nonlocal states can achieve the nonlocal advantage of quantum coherence. It is also demonstrated that the robustness of Bell nonlocality is better than nonlocal advantage of quantum coherence under the influence of the Unruh noise.

scholarly journals Quantum Entanglement and Quantum Discord of Two-Mode Gaussian States in a Thermal Environment

2011 ◽  
Vol 18 (02) ◽  
pp. 175-190 ◽  
Author(s):  
Aurelian Isar
Keyword(s):  
Sudden Death ◽  
Time Evolution ◽  
Quantum Entanglement ◽  
Quantum Discord ◽  
Thermal Environment ◽  
Quantum Correlations ◽  
Entangled State ◽  
Gaussian State ◽  
Thermal Bath ◽  
Bipartite State

In the framework of the theory of open systems based on completely positive quantum dynamical semigroups, we give a description of the continuous-variable quantum entanglement and quantum discord for a system consisting of two noninteracting modes embedded in a thermal environment. Entanglement and discord are used to quantify the quantum correlations of the system. For all values of the temperature of the thermal reservoir, an initially separable Gaussian state remains separable for all times. We study the time evolution of logarithmic negativity, which characterizes the degree of entanglement, and we show that in the case of an entangled initial Gaussian state, entanglement suppression (entanglement sudden death) takes place for non-zero temperatures of the environment. Only for zero temperature of the thermal bath the initial entangled state remains entangled for finite times. We analyze time evolution of Gaussian quantum discord, which is a measure of all quantum correlations in the bipartite state, including entanglement, and we show that quantum discord decays asymptotically in time under the effect of thermal bath. This is in contrast with the sudden death of entanglement. Before the suppression of entanglement, the qualitative evolution of quantum discord is very similar to that of the entanglement. We describe also time evolution of the degree of classical correlations and of quantum mutual information, which measures the total correlations of quantum system.

Quantum discord of a three-qubit W-class state in noisy environments

2012 ◽  
Vol 12 (7&8) ◽  
pp. 677-692
Author(s):  
Hui Guo ◽  
Jin-Ming Liu ◽  
Cheng-Jie Zhang ◽  
C. H. Oh
Keyword(s):  
Numerical Analysis ◽  
Sudden Death ◽  
Quantum Correlation ◽  
Quantum Discord ◽  
Sudden Change ◽  
Noisy Environments ◽  
Classical Correlation ◽  
Entanglement Of Formation ◽  
Sudden Transition ◽  
Bit Flip

We study the dynamics of the pairwise quantum discord (QD), classical correlation (CC), and entanglement of formation (EOF) for the three-qubit W-class state |W>_{123}=\frac 12(|100>_{123}+|010>_{123}+\sqrt{2}|001>_{123}) under the influence of various Markovian noises by analytically solving the master equation in the Lindblad form. Through numerical analysis, we find that EOF decreases asymptotically to zero with time for the dephasing noise, but it undergoes sudden death for the bit-flip noise, the isotropic noise, as well as the dissipative and noisy environments. Moreover, QD decays to zero in an asymptotical way for all the noises we investigated. Thus, when the W-class state |W>_{123} is subject to the above Markovian noises, QD is more robust than EOF against decoherence excluding the phase-flip noise, implying that QD is more useful than entanglement to characterize the quantum correlation. We also find a remarkable character for the CC in the presence of the phase-flip noise, i.e., CC displays the behavior of sudden transition and then keeps constant permanently, but the corresponding QD just exhibits a very small sudden change. Furthermore, we verify the monogamic relation between the pairwise QD and EOF of the W-class state.

scholarly journals The sudden death and sudden birth of quantum discord

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Wei Xia ◽  
Jin-Xing Hou ◽  
Xiao-Hui Wang ◽  
Si-Yuan Liu
Keyword(s):  
Sudden Death ◽  
Quantum Discord

scholarly journals EFFECTS OF CLASSICAL ENVIRONMENTAL NOISE ON ENTANGLEMENT AND QUANTUM DISCORD DYNAMICS

2012 ◽  
Vol 10 (08) ◽  
pp. 1241005 ◽  
Author(s):  
CLAUDIA BENEDETTI ◽  
FABRIZIO BUSCEMI ◽  
PAOLO BORDONE ◽  
MATTEO G.A. PARIS
Keyword(s):  
Sudden Death ◽  
Quantum Discord ◽  
Bell State ◽  
Quantum Correlations ◽  
Environmental Noise ◽  
The Other ◽  
Qualitative Behavior ◽  
Single Qubit ◽  
Other Hand ◽  
Transition Amplitudes

We address the effect of classical noise on the dynamics of quantum correlations, entanglement and quantum discord (QD), of two non-interacting qubits initially prepared in a Bell state. The effect of noise is modeled by randomizing the single-qubit transition amplitudes. We address both static and dynamic environmental noise corresponding to interaction with separate and common baths in either Markovian and non-Markovian regimes. In the Markov regime, a monotone decay of the quantum correlations is found, whereas for non-Markovian noise sudden death and revival phenomena may occur, depending on the characteristics of the noise. Entanglement and QD show the same qualitative behavior for all kind of noises considered. On the other hand, we find that separate and common environments may play opposite roles in preserving quantum correlations, depending on the noise regime considered.

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.

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