Entangled quantum heat engines based on two two-spin systems with Dzyaloshinski-Moriya anisotropic antisymmetric interaction
ABSTRACT We construct an entangled quantum heat engine (EQHE) based on two two-spin systems with Dzyaloshinski-Moriya (DM) anisotropic
antisymmetric interaction. By applying the explanations of heat transferred and work performed at the quantum level in Kieu’s
work [Phys. Rev. Lett. 93, 140403 (2004)], the basic thermodynamic quantities, i.e., heat transferred, net work done in a cycle and efficiency of EQHE
are investigated in terms of DM interaction and concurrence. The validity of the second law of thermodynamics is confirmed
in the entangled system. It is found that there is a same efficiency for both antiferromagnetic and ferromagnetic cases, and
the efficiency can be controlled in two manners: (1) only by spin-spin interaction J and DM interaction D; (2) only by the temperature T and concurrence C. In order to obtain a positive net work, we need not entangle all qubits in two two-spin systems and we
only require the entanglement between qubits in a two-spin system not be zero. As the ratio of entanglement between qubits
in two two-spin systems increases, the efficiency will approach infinitely the classical Carnot one. An interesting phenomenon
is an abrupt transition of the efficiency when the entanglements between qubits in two two-spin systems are equal.
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- "In other words each cycle comes to the end returning to the same initial state. The closure of the ST plots does not depend of the amplitudes of the driving field (the form and the area vary only), but it critically depends on frequency ω  and the module of exchange constants, that does not depend of ferromagnetic or antiferromagnetic working gas . After replacement of a frequency sign ω the circulation direction becomes opposite for all particles. "
ABSTRACT: A closed system of the equations for the local Bloch vectors and spin correlation functions is obtained by decomplexification of the Liouville-von Neumann equation for 4 magnetic particles with the exchange interaction that takes place in an arbitrary time-dependent external magnetic field. The analytical and numerical analysis of the quantum thermodynamic variables is carried out depending on separable mixed initial state and the magnetic field modulation. Under unitary evolution, non-equilibrium reversible dynamics of power production in the finite environment is investigated.
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ABSTRACT: A model of an irreversible quantum Carnot heat engine with heat resistance, internal irreversibility and heat leakage and many non-interacting harmonic oscillators is established in this paper. Based on the quantum master equation and semi-group approach, equations of some important performance parameters, such as power output, efficiency, exergy loss rate and ecological function for the irreversible quantum Carnot heat engine are derived. The optimal ecological performance of the heat engine in the classical limit is analyzed with numerical examples. Effects of internal irreversibility and heat leakage on the ecological performance are discussed. A performance comparison of the quantum heat engine under maximum ecological function and maximum power conditions is also performed.Science in China Series G Physics Mechanics and Astronomy 12/2009; 52(12):1976-1988. DOI:10.1007/s11433-009-0300-1 · 1.41 Impact Factor
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ABSTRACT: A model of a quantum heat engine with heat resistance, internal irreversibility and heat leakage and many non-interacting spin-1/2 systems is established in this paper. The quantum heat engine cycle is composed of two isothermal processes and two irreversible adiabatic processes and is referred to as a spin quantum Carnot heat engine. Based on the quantum master equation and the semi-group approach, equations of some important performance parameters, such as power output, efficiency, entropy generation rate and ecological function (a criterion representing the optimal compromise between exergy output rate and exergy loss rate), for the irreversible spin quantum Carnot heat engine are derived. The optimal ecological performance of the heat engine in the classical limit is analyzed with numerical examples. The effects of internal irreversibility and heat leakage on ecological performance are discussed in detail.Physica Scripta 01/2010; 81(2):025003. DOI:10.1088/0031-8949/81/02/025003 · 1.30 Impact Factor