DATA: 24052017
SEZIONE DI FIRENZE Filippo Caruso (LENS)
Only ideally quantum systems are closed, i.e. isolated from the rest, since they do always interact with the external environment, unavoidably affecting its coherence properties and inducing noise effects, leading to socalled open
quantum systems.
Here, we will first show this deleterious role of the environment where some information coming from the system is irreversibly lost. Then, we will discuss how there might be a backflow of information from the environment to the
system, with the dynamics showing noise time correlations and memory (nonMarkovian) effects.
However, reversing this traditional point of view, the environment may play also a crucial positive role in remarkably enhancing the quantum system performance
to achieve a given task, e.g. noiseassisted transmission of energy and information. Additionally, one can often exploit optimal control theory to manipulate part of the environment, and steer the system dynamics while being
only restricted by the socalled quantum speed limit. Moreover, since the environment does continuously 'observe' the physical system, quantum Zeno phenomena may also arise, and be analytically studied in terms of stochastic
quantum measurements by large deviation theory. Finally, the fragility of the coherence properties of the dynamical evolution against the environment noise can become an efficient tool to convert the system into a quantum probe of
external complex (even classical) objects, towards novel quantum sensing schemes.
All these theoretical analytical and numerical results, beyond their foundational role for a deeper understanding of quantum physics, have been also experimentally tested using several platforms including photonics, atomic and
biomolecular systems, with very promising and powerful reallife applications in quite different fields ranging from quantum communication to quantum biology, from quantum computation to quantum metrology.
