The Influences of Quantum Coherence on the Positive Work and the Efficiency of Quantum Heat Engine with Working Substance of Two-Qubit Heisenberg XXX Model

2018 ◽  
Vol 57 (6) ◽  
pp. 1872-1880 ◽  
Author(s):  
Hu-Ping Peng ◽  
Mao-Fa Fang ◽  
Min Yu ◽  
Hong-Mei Zou
Keyword(s):  
Quantum Coherence ◽  
Heat Engine ◽  
Quantum Heat Engine ◽  
Xxx Model ◽  
Positive Work ◽  
Heisenberg Xxx Model

scholarly journals Thermal Quantum Coherence properties in Two-Qubit Heisenberg XXX Model in Nonhomogeneous Magnetic Field

2021 ◽  
Author(s):  
Asad Ali ◽  
Muhammad Anees Khan
Keyword(s):  
Magnetic Field ◽  
Quantum Coherence ◽  
Uniform Magnetic Field ◽  
Coupling Parameter ◽  
Magnetic Interaction ◽  
Threshold Value ◽  
Quantum Correlations ◽  
Qubit System ◽  
Xxx Model ◽  
Heisenberg Xxx Model

We investigate the behavior of thermal quantum coherence in the Heisenberg XXX model for a two-qubit system placed in independently controllable Inhomogeneous magnetic fields applied to two qubits respectively. We discuss the behavior of quantum coherence by systematically varying the coupling parameter, magnetic field, and temperature for both ferromagnetic and antiferromagnetic cases. The results show the interesting behavior of quantum coherence in a certain range of parameters. Generally, it is observed that quantum correlations decay with temperature, but in the ferromagnetic case with uniform magnetic interaction, it rises with temperature up to a certain threshold value and ultimately it decreases its value to zero. Moreover, it is observed that preserving the quantum coherence for small temperatures is very hard with the increasing magnetic field because, at small temperatures, quantum coherence decays sharply with the increase in magnetic field whereas at larger temperatures it decays completely at fairly large values of the magnetic field. The variation of quantum coherence with uniform magnetic field in the antiferromagnetic case is observed to be Gaussian for larger temperature but at zero or nearly zero temperature, it behaves as a constant function for uniform magnetic field up to a threshold value and then decays to zero with an infinite slope. This shows the signature of quantum phase transition from quantum nature to classicality.

scholarly journals Revealing Trade off Relations Among Thermal Coherences and Correlations in Heisenberg XXX Model Under Inhomogeneous Magnetic Eld

2021 ◽  
Author(s):  
Asad Ali ◽  
Mustansar N Nadeem ◽  
A.H Toor ◽  
Junaid Ulhaq ◽  
Shah Ahad
Keyword(s):  
Quantum Coherence ◽  
Coupling Parameter ◽  
Quantum Fisher Information ◽  
Quantitative Relationship ◽  
Bath Temperature ◽  
Reciprocal Relationship ◽  
Entanglement Measure ◽  
Thermal Entanglement ◽  
Xxx Model ◽  
Heisenberg Xxx Model

We study the validity of quantum Fisher information (QFI) as a faithful quantum coherence and correlation quantier by drawing a comparison with subsystem's coherence measure, rst-order coherence (FOC) and the entanglement measure, Negativity to study the behavior of thermal quantum coherence and correlations in two qubit Heisenberg XXX model, placed in independently controllable magnetic eld by systematically varying the coupling parameter, magnetic eld and bath temperature for ferromagnetic and antiferromagnetic case. After carefully observing the prole of quantum coherence and correlation measures, we propose an inequality relations which shows that there may exist a quantitative relationship between QFI, Negativity and FOC in which, the equality exists at zero temperature. We identify QFI to be a more useful coherence quantier, as it quanties coherence of individual subsystems and correlations among the subsystems. On the other hand, FOC identies coherence present in the individual subsystems only. A reciprocal relationship between Negativity and FOC is also observed in dierent cases. We also observe the existence of entanglement in ferromagnetic case, in contrast to simple Heisenberg XXX model in uniform magnetic eld. We show that in the ferromagnetic case, a very small inhomogeneity in magnetic eld is capable of producing large values of thermal entanglement. This shows that the behavior of entanglement in the ferromagnetic Heisenberg system is highly unstable against inhomogeneity of magnetic elds, which is inevitably present in any solid state realization of qubits.

scholarly journals Quantum coherence in a quantum heat engine

2020 ◽  
Vol 53 (8) ◽  
pp. 085301 ◽  
Author(s):  
Yun-Hao Shi ◽  
Hai-Long Shi ◽  
Xiao-Hui Wang ◽  
Ming-Liang Hu ◽  
Si-Yuan Liu ◽  
...  
Keyword(s):  
Quantum Coherence ◽  
Heat Engine ◽  
Quantum Heat Engine

Practical implementation of aCO2-laser-coupled quantum heat engine

2005 ◽  
Vol 72 (4) ◽  
Author(s):  
Alan E. Hill ◽  
Yuri V. Rostovtsev ◽  
Marlan O. Scully
Keyword(s):  
Heat Engine ◽  
Practical Implementation ◽  
Quantum Heat Engine

Comparing Two Definitions of Work for a Biological Quantum Heat Engine

2015 ◽  
Vol 64 (4) ◽  
pp. 409-414
Author(s):  
You-Yang Xu ◽  
Juan Liu ◽  
Shun-Cai Zhao
Keyword(s):  
Heat Engine ◽  
Quantum Heat Engine
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