THERMAL ENTANGLED QUANTUM REFRIGERATOR WORKING WITH THE TWO-QUBIT HEISENBERG XX MODEL

2012 ◽  
Vol 26 (11) ◽  
pp. 1250086
Author(s):  
JI-ZHOU HE ◽  
XIAN HE ◽  
JIE ZHENG
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Coefficient Of Performance ◽  
Thermodynamic Quantities ◽  
Thermal Entanglement ◽  
First Law Of Thermodynamics ◽  
Maximum Coefficient ◽  
Constant External Magnetic Field ◽  
Xx Model ◽  
Heisenberg Xx Model

An entangled quantum refrigerator working with a two-qubit Heisenberg XX model in a constant external magnetic field is constructed in this paper. Based on the quantum first law of thermodynamics, the expressions for several basic thermodynamic quantities such as the heat transferred, the net work and the coefficient of performance are derived. Moreover, the influence of the thermal entanglement on the basic thermodynamic quantities is investigated. Several interesting features of the variation of the basic thermodynamic quantities with the thermal entanglement in zero and nonzero magnetic field are obtained. Lastly, we analyze the maximum coefficient of performance.

THE QUANTUM REFRIGERATOR IN A TWO-QUBIT XXZ HEISENBERG MODEL

2013 ◽  
Vol 27 (13) ◽  
pp. 1350055 ◽  
Author(s):  
ERHAN ALBAYRAK
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Heisenberg Model ◽  
Exchange Parameter ◽  
Thermodynamic Quantities ◽  
Two Dimensional ◽  
Different Temperatures ◽  
Constant External Magnetic Field ◽  
Xxz Heisenberg Model ◽  
Exchange Parameters

The four-level entangled quantum refrigerator (QR) is studied in the XXZ Heisenberg model for the two-qubits. The Hamiltonian of the problem includes the exchange parameters Jx = Jy = J and Jz = αJ along the x-, y- and z-directions, respectively, and constant external magnetic field B in the z-direction. The parameter α is introduced into the model which controls the strength of the exchange parameter Jz in comparison to Jx and Jy, thus, our investigation of QR includes the XX (α = 0.0), XXX (α = 1.0) and XXZ (for other α's) Heisenberg models. The two-qubits are assumed to be in contact with two heat reservoirs at different temperatures. The concurrences for a two-qubit are used as a measure of entanglement and then the expressions for the amount of heat transferred, the work performed and the efficiency are derived. The contour, i.e., the isoline maps, and some two-dimensional plots of the above mentioned thermodynamic quantities are illustrated.

scholarly journals Fluctuation Relations for Dissipative Systems in Constant External Magnetic Field: Theory and Molecular Dynamics Simulations

Entropy ◽  
2021 ◽  
Vol 23 (2) ◽  
pp. 146
Author(s):  
Alessandro Coretti ◽  
Lamberto Rondoni ◽  
Sara Bonella
Keyword(s):  
Magnetic Field ◽  
Molecular Dynamics ◽  
External Magnetic Field ◽  
Molecular Dynamics Simulations ◽  
Nonequilibrium Molecular Dynamics ◽  
Dissipative Systems ◽  
Common Belief ◽  
Fluctuation Relations ◽  
Dynamics Simulations ◽  
Constant External Magnetic Field

We illustrate how, contrary to common belief, transient Fluctuation Relations (FRs) for systems in constant external magnetic field hold without the inversion of the field. Building on previous work providing generalized time-reversal symmetries for systems in parallel external magnetic and electric fields, we observe that the standard proof of these important nonequilibrium properties can be fully reinstated in the presence of net dissipation. This generalizes recent results for the FRs in orthogonal fields—an interesting but less commonly investigated geometry—and enables direct comparison with existing literature. We also present for the first time a numerical demonstration of the validity of the transient FRs with nonzero magnetic field via nonequilibrium molecular dynamics simulations of a realistic model of liquid NaCl.

scholarly journals 1-Loop mass generation by a constant external magnetic field for an electron propagating in a thin medium

2018 ◽  
Vol 32 (10) ◽  
pp. 1850114
Author(s):  
B. Machet
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Landau Level ◽  
Mass Formula ◽  
Mass Shell ◽  
Mass Generation ◽  
Self Energy ◽  
Lowest Landau Level ◽  
Dirac Electron ◽  
Constant External Magnetic Field

The 1-loop self-energy of a Dirac electron of mass [Formula: see text] propagating in a thin medium simulating graphene in an external magnetic field [Formula: see text] is investigated in quantum field theory. Equivalence is shown with the so-called reduced QED[Formula: see text] on a 2-brane. Schwinger-like methods are used to calculate the self-mass [Formula: see text] of the electron when it lies in the lowest Landau level. Unlike in standard QED[Formula: see text], it does not vanish at the limit [Formula: see text]: [Formula: see text] on-mass-shell renormalization conditions (with [Formula: see text]); all Landau levels of the virtual electron are taken into account and are implemented. Restricting to the sole lowest Landau level of the virtual electron is explicitly shown to be inadequate. Resummations at higher orders lie beyond the scope of this work.

Propagation of a Z meson in a homogeneous magnetic field

1981 ◽  
Vol 59 (10) ◽  
pp. 1354-1358
Author(s):  
Gerry McKeon
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Effective Interaction ◽  
Homogeneous Magnetic Field ◽  
Virtual Particles ◽  
Constant External Magnetic Field

The propagation of a Z meson in a homogeneous magnetic field is studied in the context of the Salam–Weinberg model. One loop corrections to the Z propagator can contain charged virtual particles, leading to an effective interaction with a constant external magnetic field. Only the contribution of virtual charged fermions are considered in this paper.

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