Entanglement in a Two-Qubit Ising Model Under a Site-Dependent External Magnetic Field

Abstract

We investigate the ground state and the thermal entanglement in the two-qubit Ising model interacting with a site-dependent magnetic field. The degree of entanglement is measured by calculating the concurrence. For zero temperature and for certain direction of the applied magnetic field, the quantum phase transition observed under a uniform external magnetic field disappears once a very small non-uniformity is introduced. Furthermore, we have shown analytically and confirmed numerically that once the direction of one of the magnetic field is along the Ising axis then no entangled states can be produced, independently of the degree of non-uniformity of the magnetic fields on each site.

6 pages, 6 figures

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• Algebraic and group structure for bipartite three dimensional anisotropic Ising model on a non-local basis
• The Entanglement in Anisotropic Heisenberg XYZ Chain with inhomogeneous magnetic field
• Two Qubit Entanglement in $XYZ$ Magnetic Chain with DM Antisymmetric Anisotropic Exchange Interaction
• The quantification of a genuine tetrapartite entanglement in a mixed spin-(1/2,1) Heisenberg tetramer
• Generation of non-local evolution loops and exchange operations for quantum control in three dimensional anisotropic Ising model