'Nano' Implies Nonlinear Dynamics
Nano Seminar Series
R Stanley Williams, HP Labs
2:00pm - 3:00pm
Location: 390, Hearst Memorial Mining Building
One thing that we who have worked in the nano area for the past 20 years keep claiming is that new properties and opportunities arise from materials crafted at the nanometer scale. One of the major changes is that the response of materials to stimuli becomes increasingly nonlinear, and that leads to a completely new set of dynamical properties.
I will show how a single nanoscale device can be a DC-voltage controlled oscillator with periodic, chaotic, and coupled-oscillator modes, and how this behavior can be utilized in a neuromimetic circuit for computation. In the process, I will resolve a 55 year old physics conundrum through experimental data and using Leon Chua’s nonlinear dynamical circuit model to show that a single device can have regions inside it with two different current densities flowing simultaneously, and thus behave dynamically as two coupled devices. This occurs because of a temperature-driven instability, or negative differential resistance, that bifurcates to form two locally stable regions with different current densities in a process similar to a spinodal decomposition of a metastable homogeneous liquid.
This may actually be a common occurrence in modern semiconductor devices, and will require a significant change to the methods presently used for modeling current density and electric field characteristics, which may in fact be quantitatively correct on average but yield a qualitatively incorrect nanoscopic picture of current flow.
Stan Williams received a Ph.D. in physical chemistry from UC Berkeley in 1978 (Go Bears!). He was a member of technical staff at AT&T Bell Labs from 1978 to 1980 and a faculty member of the Chemistry Department at UCLA from 1980 to 1995 and director of the Memristor Research group at HP Labs until retiring this year.
For the past 30 years, his primary scientific research has been in the areas of solid-state chemistry and physics and their applications to technology. This evolved into the areas of nanostructures and chemically assembled materials, with an emphasis on the thermodynamics of size and shape.
Williams has been awarded more than 60 U.S. patents, published more than 300 papers in reviewed scientific journals and presented hundreds of invited plenary, keynote and named lectures at international scientific, technical and business events.
He has received numerous awards for business, scientific and academic achievement including the 2007 Glenn T. Seaborg Medal awarded by the UCLA Department of Chemistry.
He was named to the inaugural Scientific American 50 Top Technology leaders in 2002 and then again in 2005 (the first to be so named twice). In 2000, MIT’s Technology Review placed one of his patents among the top 5 that “will transform business and technology.”
Sponsor:Berkeley Nanosciences and Nanoengineering Institute
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