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.

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.

Non-Markovian Dynamics of Spin Squeezing Under Detuning Modulation

2017 ◽  
Vol 24 (01) ◽  
pp. 1750003
Author(s):  
Xing Xiao ◽  
Jia-Ju Wu ◽  
Wo-Jun Zhong ◽  
Yan-Ling Li
Keyword(s):  
Sudden Death ◽  
Open Systems ◽  
Spin Squeezing ◽  
Zero Temperature ◽  
Quantum Metrology ◽  
Markovian Dynamics ◽  
Long Time ◽  
Markovian Regime

The dynamics of spin squeezing of an ensemble of N separate spin-1/2 particles, each coupled to a zero-temperature non-Markovian reservoir have been investigated. We show that the initial spin squeezing could be prolonged for a long time by utilizing detuning modification. We further explore that the spin squeezing sudden death (SSSD) could be circumvented with the increasing of detuning. By comparison with the results in Markovian regime with detuning and those in non-Markovian regime without detuning, we conclude that the disappearance of SSSD and the robust preservation of spin squeezing should be attributed to the combination of detuning and non-Markovian effect. The present results may be of direct importance for quantum metrology in open systems.

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.

Dynamics of tripartite quantum correlations in mixed classical environments: The joint effects of the random telegraph and static noises

2017 ◽  
Vol 15 (05) ◽  
pp. 1750038 ◽  
Author(s):  
Lionel Tenemeza Kenfack ◽  
Martin Tchoffo ◽  
Georges Collince Fouokeng ◽  
Lukong Cornelius Fai
Keyword(s):  
Quantum Discord ◽  
Direct Interaction ◽  
Quantum Correlations ◽  
Switching Rate ◽  
Initial State ◽  
Random Telegraph Noise ◽  
Joint Effects ◽  
Telegraph Noise ◽  
Qubit System ◽  
Static Noise

In the present paper, the joint effects of two kinds of classical environmental noises, without direct interaction among each other, on the dynamics of quantum correlations (QCs) of a three-qubit system coupled in independent environments is investigated. More precisely, we join the random telegraph noise (RTN) and the static noise (SN) and focus on the dynamics of entanglement and quantum discord (QD) when the qubits are initially prepared in the GHZ- and W-type states. The overall noise affecting the qubits is obtained by combining the RTN and SN in two different setups. The results show that the disorder of the environmental noise as well as its memory qualities and the purity of the initial state considered play a crucial role in the time evolution of the system in such a way that the dynamics of QCs can be controlled by varying them. In fact, we show that, depending on the initial state and noise regime considered, the rate of collapse of QCs may either decrease or increase with the increase of the degree of disorder of the SN, the switching rate of the RTN and the purity of the initial state.

Time evolution of quantum correlations in superconducting flux-qubits under classical noises

2017 ◽  
Vol 15 (02) ◽  
pp. 1750015 ◽  
Author(s):  
Tchoffo Martin ◽  
Tsamouo Tsokeng Arthur ◽  
Fouokeng Georges Collince ◽  
Lukong Cornelius Fai
Keyword(s):  
Quantum Discord ◽  
Energy Levels ◽  
Quantum Correlations ◽  
Noise Spectrum ◽  
Entanglement Witnesses ◽  
Entanglement Measures ◽  
Flux Qubits ◽  
Common Coupling ◽  
Flux Qubit ◽  
Markovian Regime

We analyze the dynamics of both entanglement and quantum discord (QD) in a system of two non-interacting flux-qubits initially prepared in a Bell's state and subjected to either static or random telegraph noises (RTNs). Both independent and common sources of system-environment coupling are considered either in the Markovian or non-Markovian regime and the results are compared to those of ordinary qubits. Under suitable conditions, both entanglement and QD are more robust in flux-qubit systems than classical ones. In the Markovian regime where the decay is monotonic, they are both stronger in different environment coupling than in common coupling, while the opposite is found in the non-Markovian regime where the dynamics is stressed by sudden death and revival phenomena, more robust in qubits than in flux-qubits under dynamical RTN. Weakness of revival amplitudes is interpreted as a noise spectrum-related induced interaction affecting quantum features of the system, while energy level non-degeneracy (at zero-splitting) of flux-qubits induces a phase factor that set conditions under which entangled states can be experimentally witnessed in flux-qubit systems. Note that the energy levels non-degeneracy has no particular effect on other entanglement measures apart from entanglement witnesses.

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.

Effects of static noise on the dynamics of quantum correlations for a system of three qubits

2017 ◽  
Vol 31 (08) ◽  
pp. 1750046 ◽  
Author(s):  
Tenemeza Kenfack Lionel ◽  
Tchoffo Martin ◽  
Fouokeng Georges Collince ◽  
Lukong Cornelius Fai
Keyword(s):  
Open Quantum Systems ◽  
Quantum Correlations ◽  
Entangled State ◽  
Environment Interaction ◽  
Initial State ◽  
Text Type ◽  
System Environment ◽  
Entanglement Witnesses ◽  
Long Time ◽  
Static Noise

Correlations in open quantum systems exhibit peculiar phenomena under the effect of various sources of noise. Here, we investigate the dynamics of entanglement and quantum discord (QD) for three noninteracting qubits coupled with a classical environmental static noise characterized by an external random field. Two initial entangled states of the system are examined, namely, the GHZ- and [Formula: see text]-type states. The system-environment interaction is here analyzed in three different configurations, namely, independent, mixed and common environments. We find that the dynamics of quantum correlations are strongly affected by the type of system-environment interaction and the purity of the initial entangled state. Indeed, depending on the type of interaction and the value of the purity of the initial state, peculiar phenomena such as sudden death, revivals and long-time survival of quantum correlations are observed. On the other hand, our results clearly show that quantum correlations initially present in the [Formula: see text]-type states are less robust than those of the GHZ-type states. Furthermore, we find that the long-time survival of entanglement can be detected by means of the suitable entanglement witnesses.

The Dynamics of Three Different Entropic Measures of Quantum Correlations in Mixed Bipartite State Coupled with Classical Environments

2018 ◽  
Vol 17 (03) ◽  
pp. 1850023 ◽  
Author(s):  
Mahmood Shamirzaie ◽  
Salman Khan
Keyword(s):  
Quantum Discord ◽  
Conditional Entropy ◽  
Quantum Correlations ◽  
Random Telegraph Noise ◽  
Geometric Quantum Discord ◽  
Bipartite State ◽  
Telegraph Noise ◽  
Initial States ◽  
Qubit States ◽  
Static Noise

The dynamics of three different entropic measures of quantum correlations in mixed bipartite qubit states in the presence of two different classical noises, the static noise (SN) and the random telegraph noise (RTN), are investigated. The three entropic measures of quantum correlations correspond to one-way information deficit, geometric quantum discord and the cubic information. General analytic relations for each quantifier in the two configurations are obtained. In both configurations, the minimized value of each measure of quantum correlations corresponds to the conditional entropy of the same projectors. It is shown that one-way information deficit captures more correlations in highly mixed initial states. On the contrary, in both configurations the cubic information reduces to the geometric quantum discord and captures more correlations for highly pure initial states. The periodic revival of each measure of quantum correlation is more prominent in the case of RTN.

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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