Vibron transport in macromolecular chains with squeezed phonons

We investigate physical properties of a single vibronic intramolecular excitation propagating through a macromolecule, whose vibrational state can be described as a squeezed vacuum state. For a theoretical description of such a process, the partial dressing method of the vibronic excitation due to its interaction with phonons is used. We study the influence of the model parameters and strength of squeezing on the vibron dressing. It is demonstrated that for certain critical values of the model parameters a polaron crossover can occur, at which there is a sharp change in the migration nature of a vibron from the practically free to the heavy quasiparticle dressed by a phonon cloud. Increasing the strength of phonon squeezing is shown to increase the critical values of the model parameters, so that for high phonon squeezing the polaron crossover takes place in the very strong-coupling and adiabatic regime.