Noise in Classical and Quantum Systems

Noise may be defined as randomly fluctuating information that affects the evolution of a dynamical system. I will discuss how noise impacts static and dynamic properties of classical and quantum systems. Specifically, I will consider noise in the sense of stochasticity in the dynamics of classical systems (1) that arises due to interaction with the external environment, (2) that may be employed usefully to extract information pertaining to the corresponding deterministic dynamics, (3) that has its origin in the sampling of initial conditions in a finite-size system, and (4) that is induced by the application of a small external field. I will also discuss noise in the sense of unpredictability associated with measurements in quantum systems.