Information transmission of two qubits through two independent 1D Heisenberg
chains as a quantum channel is analyzed. It is found that the entanglement of
two spin-21 quantum systems is decreased during teleportation via the
thermal mixed state in 1D Heisenberg chain. The entanglement teleportation will
be realized if the minimal entanglement of the thermal mixed state is provided
in such quantum channel. High average fidelity of teleportation with values
larger than 2/3 is obtained when the temperature {\it T} is very low. The
mutual information I of the quantum channel declines with the
increase of the temperature and the external magnetic field. The entanglement
quality of input signal states cannot enhance mutual information of the quantum
channel.Comment: 11 pages, 4 figure