The statistics of work done and associated fluctuation theorems give a novel thermodynamic interpretation of dynamics in quantum systems. Here, we apply the fluctuation theorems to a sudden "quench" of a quantum system of many interacting particles containing a critical point. The results highlight that the fluctuations of a dynamical quantum system provide a route understanding the emergence of thermodynamic irreversibility. Furthermore I will show that the characteristic function of the work distribution for a non-equilibrium process can be extracted from Ramsey interferometry of a single probe qubit. Our scheme paves the way for the full characterisation of non-equilibrium processes in a variety of complex quantum systems, ranging from atomic systems to NMR.