Dynamical entanglement of vibrations in integrable dimer and small molecules

By means of the reduced-density linear entropy, we investigate the properties of dynamical entanglement of vibrations in integrable dimer and realistic small molecules which are initially in the two-mode squeezed vacuum state. It is found that the entropy of the integrable dimer is periodic for weak coupling strength c₁ and small squeezing parameter r, and there exists a beat phenomenon for strong c₁ and large r. Moreover, the entropy of the small molecules is quasi-periodic for small r, and the beat phenomenon occurs in the entropy evolution of the two molecules C ₂D₂ and SO₂ for large r. Our results might be used for molecular quantum computing based on vibrational states.