Quantum phase transition and entanglement in Heisenberg XX spin chain with impurity

In this paper, we study the quantum phase transition andthe effect of impurity on the thermal entanglement between any twolattices in three-qubit Heisenberg XX chain in a uniform magneticfield. We show that the quantum phase transition always appears whenimpurity parameter is an arbitrary constant and unequal to zero, theexternal magnetic field and impurity parameters have a great effecton it. Also, there exists a relation between the quantum phasetransition and the entanglement. By modulating the temperature,magnetic field and the impurity parameters, the entanglement betweenany two lattices can exhibit platform-like behaviour, which can beused to realize entanglement switch.