SUSAN N.
COPPERSMITH
CURRENT PROJECTS
I am a member of a collaboration led by Mark Eriksson that is working to construct a quantum computer using spin qubits composed of single-electron quantum dots fabricated in silicon/silicon-germanium heterostructures. One topic in which theory has played an important role is in understanding the impact that the degenerate valleys in the silicon band structure have on the materialŐs suitability for use for making spin qubits. We have demonstrated theoretically and experimentally that because of the sharp heterostructure interface, the electric fields generated by modulation doping, and the small size of the quantum dots, the valley degeneracy is broken and the resulting valley splitting is much larger than the spin splitting. This result is very good news for quantum computing applications.
I am collaborating with Prof. G. Gilbert of the UW-Madison Physics department to understand the structure and formation of aragonitic mollusk shell nacre. The experimental studies analyze Haliotis rufescens (red abalone) nacre with synchrotron spectromicroscopy, using linearly polarized soft-x-rays as illumination, and x-ray absorption near-edge structure (XANES) spectroscopy. Comparing experimental data from other groups and our new data with models for columnar nacre growth, we find that the data are most consistent with a model with randomly distributed nucleation sites for nacre tablets, pre-formed into organic matrix layers.
I have been studying how physics concepts can be useful for understanding issues arising in the field of computational complexity, the study of the amount of computational resources needed to solve different problems. I have been working to apply renormalization group constructions similar to those used to provide insight into phase transitions in physical systems to questions arising in computational complexity theory. The RG approach might provide new insight into how to distinguish computational problems that can and cannot be solved efficiently.
I am part of a collaboration led by David Schwartz to exploit the properties of driven flow of DNA macromolecules to perform single-molecule sequencing. Microfluidic devices to manipulate single DNA molecules must work within an integrated system to enable high-throughput biological or biochemical analysis. We are working to create a robust general platform for biological/biochemical analysis to function within an integrated system that includes massively parallel data collection and analysis.
updated 2/2007