December 2009

Donald Sprung
Department of Physics & Astronomy
McMaster University

Dear Prospective Graduate Student,

I am a theoretical physicist with broad interests and considerable experience. During the past ten years my work has mainly focussed on problems related to nanoelectronics. As the feature size of semiconductor devices decreases year by year according to Moore's law, we are approaching the scale where the motion of electrons will be governed by quantum mechanics rather than classical laws. Also, fewer and fewer electrons will be involved in recording one bit of information. This trend has sparked an explosion of interest in quantum wires and quantum dots, as people explore the principles and possibilities for the construction of future devices.

My current graduate student, completed his M.Sc. on modelling an experiment where electrons were observed escaping from an isolated, squeezed quantum dot. The interest was in understanding the shape of the barriers which define the dot. He is now looking at Bohm's interpretation of quantum mechanics, applied to the flow of electrons through a quantum dot.

A second student has just completed his M.Sc. thesis on Rabi oscillations and Zener tunneling in a biased superlattice. He studied this by solving the time dependent wave equation for a wave packet which started in a localised (Wannier) state. He has gone to McGill for a Ph.D. in Materials Science.

Many of my recent publications have concerned the propagation of electrons in finite periodic systems. This is a subject where it is easy to get started in research, and some undergraduate students have become co-authors through their involvement as Summer Research Assistants. An example is the paper by Veenstra et al. We have learned how to design an "anti-reflection coating" for electrons, which allow one to make a velocity filter.

Another topic of current interest is phase integral methods in Quantum Mechanics. The WKB approximation has a long history, yet people are always coming up with new angles and viewpoints concerning it. We have made a semi-classical coupled waves theory for one-dimensional photonic crystals, which provides analytical estimates for the band gap boundaries. They should be useful in optimising the properties of such a system.

If it appeals to you to work in a field with connections to practical developments, I would be glad to correspond with you.

regards,
Donald Sprung