  This thesis is devoted to studying two tasks: refrigeration and the creation
of correlations. In the refrigeration part, two different paradigms of cooling,
namely coherent and incoherent, are defined. The connection that these
paradigms have with other existing refrigeration techniques such as heat bath
algorithmic cooling (HBAC), the resource theoretic approach to quantum
thermodynamics, and autonomous cooling is then made. Each paradigm is then
investigated on its own. This in particular allows for the derivation of a
general and attainable bound. The bound is striking in its simplicity: it
depends on a single parameter of the environment/machine used to cool the
system of interest. The creation of correlations part is devoted to the
quantitative study of how much correlations can be created for a given amount
of energy. After having precisely formulated the problem of interest, we solve
it for arbitrary finite dimensional bipartite systems for vanishing background
temperatures. For non-vanishing background temperature the symmetry of the
problem breaks down, making it much harder to tackle. When both systems are
copies of each other, enough symmetry is restored to formulate an upper bound
valid for all (finite) dimensional systems and prove its attainability for
dimension 3 and 4. We furthermore conjecture, as well as show evidence for, the
bound to be attainable in any dimension.
