Condensed Matter Seminar Series

Measurement of Noise-Driven Switching Time Distributions of
Electrical Current in Semiconductor Superlattices

Yuriy Bomze

Duke University

Thursday January 13,  11:00 am,  Room 298,  Physics Building

Abstract:  The phenomenon of noise-driven escape from a metastable state plays an important role in a wide range of natural systems. These systems fall into two broad categories: those that are near equilibrium (e.g., chemical reactions, protein folding, biochemical networks, polymer motion) and those that are far-from-equilibrium (e.g., driven Josephson junctions, resonant tunneling systems, genetic networks, and driven mechanical oscillators). One central question that is addressed in both theoretical and experimental work is the first-passage-time distribution (FPTD) and its dependence on the control parameters. In a simple picture FPTD is expected to show exponential tails. In this talk I will report the results of the precision measurement of FPTD associated with the transition from a metastable state of electrical current in a semiconductor superlattice, a high-dimensional, far from- equilibrium system. For a certain range of the applied voltage FPTDs show the exponential tails indicative of a first passage process from an initial metastable state. However, when mean transition time becomes larger, the distributions develop power law tails with exponent dependent on applied voltage. The possible reasons for the power law behavior are discussed.