Intermolecular-interaction effects on quantum-phase dynamics of dimer systems interacting with a two-mode squeezed vacuum field

Abstract

We investigate the intermolecular-interaction (dipole–dipole interaction) effects on the quantum dynamics of dimer density matrices and photon-phase distributions using several dimer models with different intermolecular distances in the presence of a two-mode squeezed vacuum field. In this photon field, each mode is initially correlated and the reduced one-mode photon distribution is equivalent with that of a thermal field. For comparison, we perform parallel studies, in which the initial fields are two types of noncorrelated two-mode fields, i.e., a two-mode coherent field and a two-mode thermal field. It is found that although the two-mode squeezed vacuum field causes the random oscillations of dimer populations in the noninteracting dimer, the periodic oscillations like the collapse–revival behavior emerge as the intermolecular distance decreases (the intermolecular interaction increases). Similar and dissimilar features among quantum dynamics caused by these three types of fields are investigated by analyzing the dynamical behavior of two-mode Pegg–Barnett photon-phase distributions and off-diagonal dimer density matrices, which indicate the coherency between dimer states. In addition to the quantum statistical properties of initial photon field, the change in the degree of contribution between one- and two-photon processes caused by the intermolecular interaction is found to be important to determine these features.