I’ll consider chains of quantum emitters (natural or artificial atoms) weakly coupled to electromagnetic fields propagating in one-dimensional guides. Textbook open-system approach treats the field as a Markovian environment, solving the reduced emitters dynamics with Master Equations. This approach prevents one from directly accessing emitters-field entangled states. Furthermore it fails to predict the exact evolution when the field  propagating between the emitters creates feedback effects making the dynamics non-Markovian. I will show how to overcome these limitations solving the emitters-field closed dynamics with analytical and numerical tools based on the Collision Model. In the second part of the talk, I will display how Collision Model suggests operational definitions of work and heat exchanged between the emitters and the waveguide field.