Featured Speaker:  Felipe Hernández (MIT)

Title:  The semiclassical limit of noisy quantum systems

Abstract:  Although the laws of physics are quantum mechanical, the world we live in and observe is well described by classical physics. One mathematical justification for this is Egorov’s theorem which shows that the quantum and classical descriptions match as the semiclassical parameter ℏ tends to 0. However, the Ehrenfest timescale for which Egorov’s theorem holds may only be seconds or minutes for realistic systems. In this talk we consider quantum systems that are weakly coupled to a noisy external environment, as modelled by the Lindblad equation. The semiclassical limit of this Lindblad equation is a Fokker-Planck equation which includes the effects of friction and diffusion. In this talk I will show that even for very weak diffusion, the agreement between the Lindblad and Fokker-Planck equations persists for times much longer than the Ehrenfest time. This is joint work with Daniel Ranard and Jess Riedel.