Laboratoire de Physique Théorique
Toulouse - UMR 5152

The description of the dynamics resulting from the interaction of a quantum system with its environment is one of the key goals of modern quantum physics. The formal description of the evolution of an open system, especially in a quantum context, is typically tackled through master equation approach. Recently, a promising approach came to light, combining the quantum master equation and large-deviation theory. Unlike others, this approach applies to any dissipative quantum systems, paving the way to a standard description of dynamic of open quantum system in terms of thermodynamics of trajectories. From two different systems, I will explore the possibility given by this approach. Starting with a small interacting spin ring, we will see how thermodynamic of trajectories predict bistable dynamical behaviour. Next I will consider a paradigmatic system in quantum mechanics, a quantum harmonic oscillators connected to various baths. I will present how our approach, based on quantum optics methods yields an analytical expression for the large- deviation function encoding the full-counting statistics of exchange between the system and the environment. Furthermore, the same approach, generalised to any network of harmonic oscillator undergoing linear dynamics allows us to, efficiently derive numerically the behaviour of energy-exchange processes between the system in a steady state and the environment. From it we can access to possible fluctuation theorem, a key thermodynamic quantities for a large variety of open systems.