The effect of dimerization on the macroscopic tangle and thermal pairwise entanglement for a system of coupled qubits with interactions is studied. The exactly solvable model permits us to obtain analytic formulas for characteristics of the macroscopic thermal entanglement. Two special cases of the dimerization are considered: the dimerization of couplings, and the dimerization of level spacings of nearest-neighbor qubits in the chain. In the first case the dimerization of couplings essentially affects the thermal entanglement. On the other hand, the dimerization of the level spacings for qubits in the chain produces only quantitative changes in the macroscopic thermal entanglement compared to the homogeneous case.
We show that a cavity field can evolve from an initial displaced mixed thermal state to a macroscopic superpositions of displaced thermal states via resonant interaction with a two-level atom. As a macroscopic system (meter) is really in a mixed state before coupling with the microscopic system at some temperature, our result is important for studying the quantum measurement problem and decoherence under real conditions. For the two-mode case, entanglement of displaced thermal states between the modes can be obtained.