Thermal Entanglement between Alternate Qubits of a Four-qubit Heisenberg XX Chain in a Magnetic Field

Abstract

The concurrence of two alternate qubits in a four-qubit Heisenberg XX chain is investigated when a uniform magnetic field B is included. It is found that there is no thermal entanglement between alternate qubits if B is close to zero. Magnetic field can induce entanglement in a certain range both for the antiferromagnetic and ferromagnetic cases. Near zero temperature, the entanglement undergoes two sudden changes with increasing value of the magnetic field B. This is due to the changes in the ground state. This novel property may be used as quantum entanglement switch. The anisotropy in the system can also induce the entanglement between two alternate qubits.

10 pages, 3 figures

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• Unconventional strengthening of a bipartite entanglement of a mixed spin-(1/2,1) Heisenberg dimer achieved through Zeeman splitting
• XX model on the circle
• Nonequilibrium thermal entanglement in three-qubit $XX$ model
• Nonequilibrium thermal entanglement for three-spin chain
• Entanglement between distant qubits in cyclic XX chains
• Thermal entanglement of qubit pairs on the Shastry-Sutherland lattice
• The criterion for maximally entangled four-qubit state
• An Important Properties of Entanglement: Pairwise Entanglement can Only be Transferred by Entangled Pair
• Effect of three-spin interaction on thermal entanglement in Heisenberg XXZ model
• Nonlinear entanglement witnesses for four qubits in mutually unbiased bases