Even in the most sophisticated experimental laboratories, quantum systems are unavoidably affected by the sur- rounding environment. Such an action can overtone the effects one desire to observe. Beside phenomena like dissipation and approach to thermal equilibrium, which are also present in classical systems, in the context of open quantum systems environmental decoherence plays the most significant role. This is indeed responsible for the loss of the quantum coherence and thus of the quantum traits of the system dynamics. To reduce the environmental action on the system, it is essential an accurate derivation and characterization of effective equations of motion embedding such effects.

The group works on modelling and quantifying these phenomena. For instance, in the recent work [3], we addressed the possibility of decoherence due to vacuum fluctuations. Even when the radiation field is in the vacuum state, its quantum description still leaves us with non vanishing fluctuations of the electric and magnetic fields. Working within the framework of open quantum systems, we showed how one might formulate and understand the interaction of a charged particle with the unavoidable environment of vacuum fluctuations.

Another interesting scenario is when gravity plays the role of the environment causing the loss of quantum coherence. We also work on developing such models [4].

The conciliation of relativity and quantum theories has always been problematic. The reasons are mainly two. On the one side, quantum nonlocality (exemplified by the violation of Bell inequalities) creates a direct conflict with special relativistic requirements. On the other side, the unification of quantum and gravitational phenomena has not yet reached the desired goal. On top of this, one should not forget that existing relativistic quantum field theories are plagued by infinities. Crucial questions are still open: how can our world be nonlocal but at the same time be relativistic? Does gravity really need to be quantized? How is the gravitational field generated by a quantum superposition shaped? In recent years, several scientists have been proposing ideas which differ from the dominant view. For instance, in [5] Penrose highlighted the tension between the general theory of relativity and quantum superpositions.

The group is also engaged in similar investigations [6]. In particular, for a system interacting with gravitational waves, we would like to understand how the effective dynamics of the system (obtained after averaging over the gravity-waves environment) looks like and to compare the differences in predictions between a quantum and a classical treatment of gravity.