scholarly journals Nonlocal correlation in Heisenberg spin models

2017 ◽  
Vol 31 (23) ◽  
pp. 1750166 ◽  
Author(s):  
R. Muthuganesan ◽  
R. Sankaranarayanan
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Thermal Equilibrium ◽  
Quantum Discord ◽  
Spin Models ◽  
Heisenberg Spin ◽  
Geometric Quantum Discord ◽  
Nonlocal Correlation

In this paper, we investigate nonlocal correlation (beyond entanglement) captured by measurement induced nonlocality and geometric quantum discord for a pair of interacting spin-1/2 particles at thermal equilibrium. It is shown that both the measures are identical in measuring the correlation. We show that nonlocal correlation between the spins exist even without entanglement and the correlation vanishes only for maximal mixture of product bases. We also observe that while interaction between the spins is responsible for enhancement of correlation, this non-classicality decreases with the intervention of external magnetic field.

Quantum discord in a three-spin system in an external magnetic field

2014 ◽  
Vol 181 (2) ◽  
pp. 1459-1470 ◽  
Author(s):  
S. I. Doronin ◽  
E. I. Kuznetsova ◽  
E. B. Fel’dman
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Spin System ◽  
Quantum Discord

QUANTUM DISCORD IN THE THERMAL STATES OF A SPIN-STAR SYSTEM

2011 ◽  
Vol 25 (30) ◽  
pp. 2289-2297 ◽  
Author(s):  
XIAO SAN MA ◽  
GUANG XING ZHAO ◽  
JIA YAN ZHANG ◽  
AN MIN WANG
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Quantum Correlation ◽  
Quantum Discord ◽  
Anisotropy Parameter ◽  
Interaction Strength ◽  
The Other ◽  
Star System ◽  
Star Model ◽  
Thermal States

We investigate the quantum discord in the thermal states for a spin-star model consisting of three parties which include one central spin and the other two outer spins. Our results imply that the quantum correlation can be established between the two outer spins both of which interacting with the central spin independently. From the analysis, we find that the quantum discord and entanglement depends not only on the external magnetic field and the interaction strength but also on the anisotropy parameter and the temperature. Specially, the quantum discord is more robust than the quantum entanglement in the sense that the quantum discord lasts for higher temperatures than the entanglement does.

scholarly journals Thermodynamic properties of Heisenberg spin systems on a square lattice with the Dzyaloshinskii--Moriya interaction

2020 ◽  
Vol 20 (1) ◽  
pp. 63-73
Author(s):  
Vitalii Kapitan ◽  
◽  
Egor Vasiliev ◽  
Yuriy Shevchenko ◽  
Alexander Perzhu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
External Magnetic Field ◽  
Thermodynamic Properties ◽  
Spin Systems ◽  
Square Lattice ◽  
Temperature Behaviour ◽  
Heisenberg Spin ◽  
Moriya Interaction

We present results of numerical simulation of thermodynamics for array of Classical Heisenberg spins placed on 2D square lattice. By using Metropolis and Wang--Landau methods we show the temperature behaviour of system with competing Heisenberg and Dzyaloshinskii--Moriya interaction (DMI) in contrast with classical Heisenberg system. We show the process of nucleating of skyrmion depending on the value of external magnetic field.

scholarly journals Spin models in complex magnetic fields: a hard sign problem

2018 ◽  
Vol 175 ◽  
pp. 07026 ◽  
Author(s):  
Philippe de Forcrand ◽  
Tobias Rindlisbacher
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Partition Function ◽  
External Field ◽  
Potts Model ◽  
Cluster Algorithm ◽  
Spin Models ◽  
Sign Problem ◽  
Special Cases ◽  
Severe Sign

Coupling spin models to complex external fields can give rise to interesting phenomena like zeroes of the partition function (Lee-Yang zeroes, edge singularities) or oscillating propagators. Unfortunately, it usually also leads to a severe sign problem that can be overcome only in special cases; if the partition function has zeroes, the sign problem is even representation-independent at these points. In this study, we couple the N-state Potts model in different ways to a complex external magnetic field and discuss the above mentioned phenomena and their relations based on analytic calculations (1D) and results obtained using a modified cluster algorithm (general D) that in many cases either cures or at least drastically reduces the sign-problem induced by the complex external field.

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