Title:  The Tipping Point:  How Does A Little Noise Make a Big Difference?

Daniel Stein, NY University. 

Abstract: Small random fluctuations, either of thermal or quantum origin, are
the cause of many important and interesting physical phenomena. These include
chemical reactions, nucleation in phase transitions (i.e., the formation of a
droplet of one phase within another phase), and the formation of unusual
spatially localized states in various condensed matter systems. In all of
these, random fluctuations (or `noise'), no matter how small, eventually
drives a physical system from one stable state to another.

We consider both classical and quantum noise, and discuss how thermally
activated hopping over a barrier crosses over to quantum tunneling through a
barrier as temperature is lowered.  This crossover has some (but not all)
features of a second-order phase transition.  We also discuss two timely
applications from mesoscopic physics: thermally induced breakup of monovalent
metallic nanowires, and stochastic reversal of magnetization in thin
ferromagnetic annuli. Each are of interest both from the point of view of
fundamental physics and for potential technological applications.