Lab Home | Phone | Search
Center for Nonlinear Studies  Center for Nonlinear Studies
 Colloquia Archive 
 Postdoc Seminars Archive 
 Quantum Lunch 
 CMS Colloquia 
 Q-Mat Seminars 
 Q-Mat Seminars Archive 
 Kac Lectures 
 Dist. Quant. Lecture 
 Ulam Scholar 
 Summer Research 
 Student Application 
 Past Visitors 
 PD Travel Request 
 History of CNLS 
 Maps, Directions 
 CNLS Office 
Monday, April 20, 2009
3:00 PM - 4:00 PM
CNLS Conference Room (TA-3, Bldg 1690)


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

Daniel Stein
New York University

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. In classical field theories, a crossover between different activation behaviors occurs as one or more control parameters are varied. This crossover has some (but not all) features of a second-order phase transition. This transition shares a number of features with the well-known crossover from thermally activated hopping to quantum tunneling through a barrier as temperature is lowered in certain quantum field theories. 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, some of which will be discussed.

Host: Cristiano Nisoli, T-4/CNLS