Effectiveness of Non-Markovian Methods for Quantum Discord Dynamics of Non-coupled Two-Qubit System

2018 ◽  
Vol 70 (3) ◽  
pp. 268 ◽  
Author(s):  
Yong-Gang Huang ◽  
Xiao-Yun Wang ◽  
Xue-Xian Yang ◽  
Ke Deng ◽  
Jin-Zhang Peng ◽  
...  
Keyword(s):  
Quantum Discord ◽  
Qubit System

scholarly journals Dynamics of entanglement and non-classical correlation for four-qubit GHZ state

2015 ◽  
Vol 13 (06) ◽  
pp. 1550044 ◽  
Author(s):  
P. Espoukeh ◽  
R. Rahimi ◽  
S. Salimi ◽  
P. Pedram
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Discord ◽  
Quantum Information Processing ◽  
Ghz State ◽  
Classical Correlation ◽  
Qubit System ◽  
The Many ◽  
Sudden Transition

Many-qubit entanglement is crucial for quantum information processing although its exploitation is hindered by the detrimental effects of the environment surrounding the many-qubit system. It is thus of importance to study the dynamics of general multipartite non-classical correlation, including but not restricted to entanglement, under noise. We did this study for four-qubit Greenberger–Horne–Zeilinga (GHZ) state under most common noises in an experiment and found that non-classical correlation is more robust than entanglement except when it is imposed to dephasing channel. Quantum discord presents a sudden transition in its dynamics for Pauli-X and Pauli-Y noises as well as Bell-diagonal states interacting with dephasing reservoirs and it decays monotonically for Pauli-Z and isotropic noises.

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.

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.

scholarly journals Quantum Darwinism in a Composite System: Objectivity versus Classicality

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 995
Author(s):  
Barış Çakmak ◽  
Özgür E. Müstecaplıoğlu ◽  
Mauro Paternostro ◽  
Bassano Vacchini ◽  
Steve Campbell
Keyword(s):  
Hilbert Space ◽  
Quantum System ◽  
Quantum Discord ◽  
Composite System ◽  
Analytical Expression ◽  
Composite Systems ◽  
Composite Quantum System ◽  
Qubit System ◽  
Quantum Darwinism ◽  
Decoherence Free Subspace

We investigate the implications of quantum Darwinism in a composite quantum system with interacting constituents exhibiting a decoherence-free subspace. We consider a two-qubit system coupled to an N-qubit environment via a dephasing interaction. For excitation preserving interactions between the system qubits, an analytical expression for the dynamics is obtained. It demonstrates that part of the system Hilbert space redundantly proliferates its information to the environment, while the remaining subspace is decoupled and preserves clear non-classical signatures. For measurements performed on the system, we establish that a non-zero quantum discord is shared between the composite system and the environment, thus violating the conditions of strong Darwinism. However, due to the asymmetry of quantum discord, the information shared with the environment is completely classical for measurements performed on the environment. Our results imply a dichotomy between objectivity and classicality that emerges when considering composite systems.

Dynamics of quantum discord for a two-qubit system

2013 ◽  
Vol 9 (1) ◽  
pp. 69-72 ◽  
Author(s):  
Xiong Yang ◽  
Jia-hua Xiao
Keyword(s):  
Quantum Discord ◽  
Qubit System

Studying quantum correlations dynamics in the phase space for continuous-variable Werner states and Bell-diagonal states

2019 ◽  
Vol 16 (07) ◽  
pp. 1950109
Author(s):  
Fatima-Zahra Siyouri ◽  
Hicham Ait Mansour ◽  
Fadoua Elbarrichi
Keyword(s):  
Wigner Function ◽  
Quantum Discord ◽  
Open Quantum Systems ◽  
Quantum Correlations ◽  
Continuous Variable ◽  
Quantum Systems ◽  
Qubit System ◽  
Classical Correlations ◽  
Werner States ◽  
System F

We investigate the ability of Wigner function to reveal and measure general quantum correlations in two-qubit open system. For this purpose, we analyze comparatively their dynamics for two different states, continuous-variable Werner states (CWS) and Bell-diagonal states (BDS), independently interacting with dephasing reservoirs. Then, we explore the effects of decreasing the degree of non-Markovianity on their behavior. We show that the presence of both quantum entanglement and quantum discord allow to have a negative Wigner function, in contrast to the result obtained for the closed two-qubit system [F. Siyouri, M. El Baz and Y. Hassouni, The negativity of Wigner function as a measure of quantum correlations, Quantum Inf. Process. 15(10) (2016) 4237–4252]. In fact, we conclude that negativity of Wigner function can be used to capture and quantify the amount of general non-classical correlations in open quantum systems.

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