Quantum correlations and thermal machines

In this thesis, we explore it in the context of thermodynamics: looking at what kind of thermal devices can be constructed and how quantum behaviour affects them. We consider three research strands.

In the first part we formulate a selection of heat engines with two-qubit systems, utilising environments that induce quantum correlations into the system. We see that these correlations can have some effects on the work of the engine, but this effect is system dependent. <br><br>Describing the dynamics of a quantum system in contact with an external environment is often achieved with a master equation. When considering systems comprised of multiple subsystems, the description becomes more complicated and some of the master equations that have been used previously produce unphysical results.