Quantum entanglement, as one of the most fundamental features of quantum theory, is the primary source of nonclassical correlations between subsystems and plays a crucial role in quantum energy and information transport phenomena. Investigating the thermal behavior of entanglement in simple systems, such as two-qubit models, provides an effective framework for analyzing the fundamental mechanisms governing quantum heat conduction. In this study, a two-qubit system with anisotropic interactions of the Dzyaloshinskii–Moriya (DM) and KSEA types was examined under an external magnetic field. To characterize the quantum correlations, two complementary measures are employed: negativity as an indicator of entanglement, and local quantum Fisher information (LQFI) as a measure of quantum correlations beyond entanglement. Numerical analysis reveals that the anisotropic structure of spin–spin interactions play a decisive role in the stability of entanglement at various temperatures. In particular, the presence of both DM and KSEA components can enhance the preservation of quantum correlations in the low-temperature regime, whereas the external magnetic field tends to suppress them. These findings provide new insights into the role of quantum correlations in the thermal processes of small-scale systems.
Abstract We employ entanglement negativity, local quantum uncertainty (LQU), and local quantum Fisher information (LQFI) to characterize thermal entanglement between two XYZ-Heisenberg-qubit states under the influence of Dzyaloshinsky-Moriya(DM) and Kaplan-Shekhtman-Entin-Wohlman-Aharony (KSEA) interactions, as well as a magnetic field and thermal equilibrium temperature. A comparative examination reveals similar behaviors among these correlation measures. For the antiferromagnetic scenario, we observe that increasing the DM interaction parameter D z enhances thermal entanglement. Conversely, in the ferromagnetic case, the behavior of thermal entanglement differs with varying D z . Additionally, employing Kraus operators, we explore the performance of these quantifiers under decoherence. Notably, LQFI exhibits greater robustness than negativity and LQU, even displaying a frozen phenomenon at some time under dephasing effects.
In this paper, we investigate the pairwise quantum correlations in a two-qubit anisotropic Heisenberg model under the interplay of Calogero–Moser (CM) and Dzyaloshinsky–Moriya (DM) interactions in the presence of the homogeneous and inhomogeneous magnetic fields. We employ, respectively, the logarithmic negativity and local quantum uncertainty (LQU) to characterize the degree of entanglement and the amount of quantum correlations between the two parties of the considered system in equilibrium with a thermal reservoir. We analyze and compare the behaviors of the two quantum correlation quantifiers in the thermal state of the chain spin system and we discuss how relative distance between spins, equilibrium temperature, DM interaction coupling parameter and the external magnetic fields strengths influence the variations of both quantum correlation measures in such system.
Abstract The thermal quantum correlations’ dynamics of an anisotropic two-qubit Heisenberg XYZ model in the presence of a x-projection external magnetic field are investigated in this paper. We use local quantum-Fisher information (LQFI), and log-negativity, and local quantum-uncertainty (LQU) to analyze the generated quantum correlation dynamics. Using the associated parameters, we demonstrate the successful generation of entanglement and quantum correlations beyond entanglement in the anisotropic spin-chain state. Certain values and ranges of anisotropy, external magnetic field, and spin coupling strength are proposed that can be used to achieve either a non-maximal or maximal quantum correlated state. The characterization of the spin-chain state by various parameters determines the dynamical patterns, degree, and preservation limits of the associated quantum correlations. Finally, the LQFI, LQU, and log-negativity functions’ robustness is highly dependent on their parameters, and they rarely agree on the degree of quantum correlations and dynamical patterns.
We study thermal quantum correlations and coherence in Heisenberg
XY model with anisotropic interactions under a uniform magnetic field $ B $. Using concurrence
C, local quantum uncertainty (LQU), Bell-Clauser-Horne-Shimony-Holt (CHSH) nonlocality $ \mathbb{B}$, and coherence
Cl as quantifiers, we analyze how magnetic anisotropy $ δ_m $, coupling anisotropy $ δ_c $, Dzyaloshinskii-Moriya (DM) interaction $ D $, temperature $ T $, and magnetic field $ B $ modulate quantum resources. At low temperatures and relevant magnetic fields, the entanglement is maximized, but exhibits sudden death for $ δ_m = 0 $, which turns into a smooth decay as $ δ_m $ increases, highlighting its stabilizing role. LQU shows that stronger anisotropy suppresses quantum correlations, while $ \mathbb{B} $ induces a non-monotonic response peaking at a critical field $ B_c
.Bell−CHSHnonlocalityviolations( \mathbb{B} > 2 $) persist below $ B_c
,butthermalnoise( T \geq 1 $) suppresses them. Coherence $ C_l $ is most robust to thermal fluctuations, especially for high
δm, which also dampens abrupt quantum phase transitions. The DM interaction is essential for entanglement generation, with $ D $ and anisotropy synergistically enhancing correlation resilience. We identify a hierarchy of thermal degradation: nonlocality ($ \mathbb{B}
)vanishesfirst,followedbyentanglement( C $), then general quantum correlations (LQU), while coherence $ C_l $ persists the longest. These results demonstrate tunable control of quantum resources via anisotropy and external parameters, providing insights for the design of robust spin-based quantum technologies.
Thermal quantum and total correlations of a two spin-1 Ising model in the presence of an external homogeneous magnetic field and the Dzyaloshinski—Moriya (DM) interaction are investigated. The result indicates that the DM interaction plays a leading role in the quantum correlation measured by measurement-induced disturbance except for the region with small DM interaction and low temperature, while the DM interaction and the external magnetic field play competing roles in the negativity. The thermal total correlations measured by an alternative new measure defined in terms of the Wigner—Yanase skew information and the quantum mutual information display differences in the same region.
In this paper, a two-spin-1/2 particle coupled via dipolar interaction with the interplay of antisymmetric Dzyaloshinskii–Moriya and symmetric Kaplan–Shekhtman–Entin–Wohlman–Aharony interactions is considered at thermal equilibrium. The local quantum uncertainty and local quantum Fisher information are investigated as the pairwise nonclassical correlations quantifiers. The effects of the different system parameters on the quantified quantum correlation are analyzed in detail. Our results showed that the two studied thermal quantum correlation measures have similar qualitative behavior as well as quantitative sometimes. Also, it is shown that the quantumness of correlations is lost as the temperature rises sufficiently. Nevertheless, the antisymmetric and symmetric contributions of spin-orbit coupling considerably improve the amount of quantum correlations. Our analysis emphasized also that the local quantum uncertainty is bounded by local quantum Fisher information.