Date/Time
Date(s) - 14/01/2015
3:30 pm - 4:30 pm

Title: Thermalization and Entanglement in Quantum Systems

Speaker: Dr. Alioscia Hamma

Institute: Perimeter Institute

Location: ABB 102

Description:

The most familiar fact of physics in our experience is that physical systems spontaneously tend to reach equilibrium and thermalize. This very basic fact has always been at odds with the fundamental laws of physics, that are time-reversal. In particular, quantum dynamics in an isolated system is unitary, reversible and no entropy can increase. The key to understanding thermalization in quantum mechanics is Entanglement. Entanglement is the impossibility of separating a quantum system in sub-systems. In practice, this means that entropy in subsystems increases even if globally the whole system has zero entropy. In this Colloquium, I will illustrate the fact that, because of entanglement, not only thermalization can happen, but it happens (almost) always. As we shall see, this fact is at also at the root of the classicality of macroscopic world. This leaves us with a very important question, is it possible in principle to have a quantum system that refuses to thermalize? Or, in other worlds, can we build a quantum hard drive? I will offer some tentative solutions to this problem, and illustrate the challenges and problems that still have to be faced from the theoretical and experimental point of view.