On the influence of the "donor"/"acceptor" presence on the excitation states in molecular chains: non-adiabatic polaron approach

In the paper, we considered a molecular structure that consists of a molecular chain and an additional molecule ("donor"/"acceptor") that can inject (or remove) single excitation (vibron, electron, e.t.c.) onto the molecular chain. We assumed that the excitation forms a self-trapped state due to the interaction with mechanical oscillations of chain structure elements. We analyzed the energy spectra of the excitation and showed that its state (when it migrates to the molecular chain) has the properties of the non-adiabatic polaron state. The conditions under which the excitation can migrate from one subsystem to another were considered. It was shown that the presence of a "donor" molecule cannot significantly change the properties of the excitation located on the molecular chain. At the same time, the molecular chain can affect the position of the energy level of the excitation localized on the "donor" subsystem. Indirectly, this can influence the process of excitation migration from one subsystem to another one. The influence of basic energy parameters of the system and the environment temperature on this process are discussed. The entire system was assumed to be in thermal equilibrium with the environment

Electromagnetic pulse transparency in coupled cavity arrays through dispersion management

We theoretically demonstrated the possible emergence of slow-light self-induced transparency solitons in the infinite one-dimensional coupled cavity array, with each cavity containing a single qubit. We have predicted a substantial dependence of pulse transparency on its dimensionless width $\tau_0$. In particular, short pulses whose widths range from $\tau_0\ll 1$ to $\tau_0\lesssim 1$ exhibit simple, almost linear dispersion law with a finite frequency gap of the order of the cavity array photonic band gap. That is, the medium is opaque for very short pulses with carrier wave frequency below the photonic gap. When the pulse width exceeds the critical one, a twin transparency window separated by a finite band gap appears in the soliton pulse dispersion law. Observation of predicted effects within the proposed setup would be of interest for understanding the properties of self-induced transparency effect in general and future applications in the design of quantum technological devices

Qubit-Photon Bound States in Superconducting Metamaterials

We study quantum features of electromagnetic radiation propagating in the one-dimensional superconducting quantum metamaterial comprised of an infinite chain of charge qubits placed within two-stripe massive superconductive resonators. The Quantum-mechanical model is derived assuming weak fields and that, at low temperatures, each qubit is either unoccupied ($N=0$) or occupied by a single Cooper pair ($N=1$). Based on this assumption we demonstrate the emergence of two bands of single-photon-qubit bound states with the energy lying within (lower branch) or outside (higher) the photon continuum. The emergence of bound states may cause radiation trapping which could be of interest for the control of photon transport in these systems