Entanglement teleportation via a couple of quantum channels in Ising–Heisenberg spin chain model of a heterotrimetallic Fe–Mn–Cu coordination polymer

We investigate the teleportation of an entangled state via a couple of quantum channels, which are composed of a spin-1/2 Heisenberg dimer in two infinite Ising–Heisenberg chains. The heterotrimetallic coordination polymer CuⅡMnⅡ(L1)][FeⅢ(bpb)(CN)2]·ClO4·H2O(abbreviated as Fe–Mn–Cu) can be regarded as an actual material for this chain.We apply the transfer-matrix approach to obtain the density operator for the Heisenberg dimer and use the standard teleportation protocol to derive the analytical expression of the density matrix of the output state and the average fidelity of the entanglement teleportation. We study the effects of the temperature T, anisotropy coupling parameter △, Heisenberg coupling parameter J2 and external magnetic field h on the quantum channels. The results show that anisotropy coupling? and Heisenberg coupling J2 can favor the generation of the output concurrence and expand the scope of the successful average fidelity.

Thermal entanglement in a spin-1/2 Ising-Heisenberg butterfly-shaped chain with impurities

We investigate the effect of impurities on the thermal entanglement in a spin-1/2 Ising-Heisenberg butterfly-shaped chain,where four interstitial Heisenberg spins are localized on the vertices of a rectangular plaquette in a unit block.By using the transfer-matrix approach,we numerically calculate the partition function and the reduced density matrix of this model.The bipartite thermal entanglement between different Heisenberg spin pairs is quantified by the concurrence.We also discuss the fluctuations caused by the impurities through the uniform distribution and the Gaussian distribution.Considering the effects of the external magnetic field,temperature,Heisenberg and Ising interactions as well as the parameter of anisotropy on the thermal entanglement,our results show that comparing with the case of the clean model,in both the twoimpurity model and the impurity fluctuation model the entanglement is more robust within a certain range of anisotropic parameters and the region of the magnetic field where the entanglement occurred is also larger.