scholarly journals Thermal quantum and classical correlations in a two-qubit XX model in a nonuniform external magnetic field

2010 ◽  
Vol 43 (48) ◽  
pp. 485302 ◽  
Author(s):  
Ali Saif M Hassan ◽  
Behzad Lari ◽  
Pramod S Joag
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Classical Correlations ◽  
Xx Model ◽  
Quantum And Classical Correlations

Adiabatic demagnetization at absolute negative temperature: Generation of quantum correlations

2019 ◽  
Vol 17 (03) ◽  
pp. 1950023
Author(s):  
Gregory B. Furman ◽  
Shaul D. Goren ◽  
Victor M. Meerovich ◽  
Vladimir L. Sokolovsky
Keyword(s):  
Magnetic Field ◽  
Negative Temperature ◽  
Quantum Correlations ◽  
Zero Magnetic Field ◽  
Positive Temperature ◽  
Nuclear Spins ◽  
Adiabatic Demagnetization ◽  
Negative Temperatures ◽  
Classical Correlations ◽  
Quantum And Classical Correlations

In this paper, we study behavior of the correlations, both quantum and classical, under adiabatic demagnetization process in systems of nuclear spins with dipole–dipole interactions in an external magnetic field and in the temperature range including positive and negative temperatures. For a two-spin system, analytical expressions for the quantum and classical correlations are obtained. It is revealed that the field dependences of the quantum and classical correlations at positive and negative temperatures are substantially different. This difference most clearly appears in the case of zero magnetic field: at negative temperature, the measures of quantum correlations tend to the maximum values with a temperature increase. At positive temperature, these quantities tend to zero at a decrease of magnetic field. It is also found that, for the nearest-neighboring spins in the same field, the values of concurrence and discord are larger at negative temperatures than at positive ones.

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.

RECOIL IMPLANTATION MÖSSBAUER EXPERIMENT ON 57Fe IN Ge IN THE PRESENCE OF AN EXTERNAL MAGNETIC FIELD

1980 ◽  
Vol 41 (C1) ◽  
pp. C1-445-C1-445
Author(s):  
G. Langouche ◽  
N. S. Dixon ◽  
L. Gettner ◽  
S. S. Hanna
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Recoil Implantation
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