Symmetries, decoherence and the quantum to classical transition
Quantum theory is the current framework that is used to understand the fundamental constituent of the Universe. Contrary to classical physics, it has many non intuitive features rooted in the superposition principle and embodied in the famous Schrödinger’s cat paradox. What this paradox illustrates are the difficulties to apply quantum concepts into our classical world and naturally leads to the question of how to understand the quantum to classical transition.
Decoherence is our best physical mechanism to understand this quantum to classical transition. From a conceptual perspective, the underlying idea behind this phenomenon is that every system is never isolated from an unmonitored environment, whatever care the experimentalist is putting in the design of her/his experiment. Information about the state of the system is always lost in the environment and this leakage leads to the effective destruction of the quantum interference pattern.
To be more precise, what controls the decoherence process and the emergence of a classical description is mostly the interaction between the system and its environment. In principle, once we know the interaction, we could determine how the transition occurs. In practice, the most efficient approach is to set up an effective model, like the quantum Brownian motion, and compare it to our experiments. However, we know it is possible to deduce the fundamental interactions in the context of quantum field theory from very general symmetry principles. Knowing this, a natural question to ask is then if we can find a direct link between the symmetries underlying the fundamental interactions and the emergence of classical behavior induced by the interaction betweens systems and environments.
The goal of this project is to have a better understanding of the relationship between symmetries and which pointer states will emerge after a decoherence process.