Energy and information propagation in a finite coupled bosonic heat bath

The finite coupled bosonic model of reservoir introduced by Vasile et al. [Phys. Rev. A 89 (2014) 022109] to characterize non-Markovianity, is used to study the different dissipative behaviors of a harmonic oscillator coupled to it when it is in resonance, close to resonance or far detuned. We show that information and energy exchange between system and heat bath go hand in hand because phonons are the carriers of both: in resonance free propagation of excitations is achieved, and therefore pure dissipation, while when far detuned the system can only correlate with the first oscillator in the bath's chain, leading to almost unitary evolution. In the intermediate situation, we show the penetration of correlations and the formation of oscillatory (dressed state) behavior, which lies at the root of non-Markovianity.