Nonlocal advantage of quantum coherence and quantum discord versus internal energy in the Heisenberg chain

2021 ◽  
Vol 20 (7) ◽  
Author(s):  
Yu-Xia Xie ◽  
Xiao-Xiao Xu
Keyword(s):  
Internal Energy ◽  
Quantum Coherence ◽  
Quantum Discord ◽  
Heisenberg Chain

scholarly journals Effects of phase shift on bipartite and multipartite correlations of a spin chain under dephasing

Open Physics ◽  
2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Ai-Xi Chen ◽  
Jian-Song Zhang
Keyword(s):  
Steady State ◽  
Phase Shift ◽  
Analytical Solution ◽  
Spin Chain ◽  
Quantum Discord ◽  
Present Model ◽  
Spin Squeezing ◽  
Heisenberg Chain ◽  
Initial Correlations ◽  
Long Time

AbstractWe investigate the effects of phase shift on entanglement, quantum discord, geometric discord, and spinsqueezing of a Heisenberg chain under dephasing. An analytical solution of the present model is obtained. Our results show that the initial correlations of the spin chain could be partially stored for a long time in the presence of dephasing and the amount of steady state correlations can be adjusted via phase shift. Particularly, we find the effects of phase shift on quantum discord and geometric discord are not always the same, i.e., the increase of geometric discord does not always imply the increase of quantum discord. Then, we calculate the spin-squeezing of the spin chain and find that spin-squeezing first increases with time and then reaches a plateau. The amount of spin-squeezing can be controlled via phase shift.

scholarly journals Thermal quantum discord in the Heisenberg chain with impurity

2014 ◽  
Vol 444 ◽  
pp. 40-43 ◽  
Author(s):  
Jia-Min Gong ◽  
Zhan-Qiang Hui
Keyword(s):  
Quantum Discord ◽  
Heisenberg Chain

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 discord and quantum phase transition in spin-1/2 frustrated Heisenberg chain

2013 ◽  
Vol 13 (5&6) ◽  
pp. 452-468
Author(s):  
Chu-Hui Fan ◽  
Heng-Na Xiong ◽  
Yixiao Huang ◽  
Zhe Sun
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Quantum Discord ◽  
Nearest Neighbor ◽  
Finite Size ◽  
Quantum Phase ◽  
Nonlinear Dependence ◽  
Heisenberg Chain ◽  
Transition Points ◽  
Analytical Result

By using the concept of the quantum discord (QD), we study the spin-1/2 antiferromagnetic Heisenberg chain with next-nearest-neighbor interaction. Due to the $SU(2)$ symmetry and $Z_{2}$ symmetry in this system, we obtain the analytical result of the QD and its geometric measure (GMQD), which is determined by the two-site correlators. For the 4-site and 6-site cases, the connection between GMQD (QD) and the eigenenergies was revealed. From the analytical and numerical results, we find GMQD (QD) is an effective tool in detecting the both the first-order and the infinite-order quantum-phase-transition points for the finite-size systems. Moreover, by using the entanglement excitation energy and a universal frustration measure we consider the frustration properties of the system and find a nonlinear dependence of the GMQD on the frustration.

scholarly journals Quantum coherence versus nonclassical correlations in optomechanics

2019 ◽  
Vol 33 (29) ◽  
pp. 1950343
Author(s):  
Y. Lahlou ◽  
M. Amazioug ◽  
J. El Qars ◽  
N. Habiballah ◽  
M. Daoud ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Quantum Coherence ◽  
Quantum Discord ◽  
Thermal Noise ◽  
Superposition Principle ◽  
Quantum Correlations ◽  
Entanglement Of Formation ◽  
Mechanical Subsystem ◽  
Optomechanical Coupling ◽  
Gaussian Quantum Discord

Coherence arises from the superposition principle, where it plays a central role in quantum mechanics. In Phys. Rev. Lett. 114, 210401 (2015), it has been shown that the freezing phenomenon of quantum correlations beyond entanglement is intimately related to the freezing of quantum coherence (QC). In this paper, we compare the behavior of entanglement and quantum discord with quantum coherence in two different subsystems (optical and mechanical). We use respectively the entanglement of formation (EoF) and the Gaussian quantum discord (GQD) to quantify entanglement and quantum discord. Under thermal noise and optomechanical coupling effects, we show that EoF, GQD and QC behave in the same way. Remarkably, when entanglement vanishes, GQD and QC remain almost unaffected by thermal noise, keeping nonzero values even for high-temperature, which is in concordance with Phys. Rev. Lett. 114, 210401 (2015). Also, we find that the coherence associated with the optical subsystem is more robust — against thermal noise — than those of the mechanical subsystem. Our results confirm that optomechanical cavities constitute a powerful resource of QC.

Dynamics of coherence under Markovian and non-Markovian environments

2017 ◽  
Vol 31 (35) ◽  
pp. 1750329 ◽  
Author(s):  
Zhong-Xiao Wang ◽  
Teng Ma ◽  
Shu-Hao Wang ◽  
Tie-Jun Wang ◽  
Chuan Wang
Keyword(s):  
Density Matrix ◽  
Upper Bound ◽  
Quantum Coherence ◽  
Quantum Discord ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Initial State ◽  
Single Qubit ◽  
Markovian Processes ◽  
Markovian Dynamics

The behavior of quantum coherence is studied under Markovian and non-Markovian dynamics for open quantum systems. For single qubit systems, we show that the coherence depending on the off-diagonal elements of the density matrix is the upper bound of the coherence depending on the relative entropy under both Markovian and non-Markovian processes. For two-qubit systems, in both Markovian and non-Markovian processes, quantum discord and coherence show less sensitivity to the initial state than quantum entanglement. We also find that the quantum discord has similar behaviors with coherence under both Markovian and non-Markovian dynamics.

scholarly journals QUANTUM DISCORD AS A RESOURCE IN QUANTUM COMMUNICATION

2012 ◽  
Vol 27 (01n03) ◽  
pp. 1345041 ◽  
Author(s):  
VAIBHAV MADHOK ◽  
ANIMESH DATTA
Keyword(s):  
Quantum State ◽  
Quantum Coherence ◽  
Quantum Discord ◽  
Quantum Communication ◽  
Quantum States ◽  
Quantitative Relation ◽  
Dense Coding ◽  
Open Questions ◽  
Communication Processes ◽  
Quantum Protocols

As quantum technologies move from the issues of principle to those of practice, it is important to understand the limitations on attaining tangible quantum advantages. In the realm of quantum communication, quantum discord captures the damaging effects of a decoherent environment. This is a consequence of quantum discord quantifying the advantage of quantum coherence in quantum communication. This establishes quantum discord as a resource for quantum communication processes. We discuss this progress, which derives a quantitative relation between the yield of the fully quantum Slepian–Wolf (FQSW) protocol in the presence of noise and the quantum discord of the state involved. The significance of quantum discord in noisy versions of teleportation, super-dense coding, entanglement distillation and quantum state merging are discussed. These results lead to open questions regarding the tradeoff between quantum entanglement and discord in choosing the optimal quantum states for attaining palpable quantum advantages in noisy quantum protocols.

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