The entanglement between the boundary qubits in the five-qubit Heisenberg XX open chain
量子位Heisenberg XX开链中边界量子位之间的纠缠

Heisenberg XX open chain is very important in the study of quantum state transition. In this paper, we calculate the entanglement between the boundary qubits in the five-qubit Heisenberg XX open chain. When introducing magnetic impurity and system impurity and they satisfy linear relation, the system can be solved exactly, and there exist entanglement between the boundary qubits. Choosing the magnetic and system impurity properly, the boundary entanglement can get the maximal value 0.5.