Overview
News from our Group
- We have new PIMC results on the role of correlation in exchange coupling of spins in quantum dots and optical lattices. (arXiv:0809.0038 and an interactive tool on nanoHUB).
- Prof. Shumway is on sabbatical at Cornell University through June, 2009.
- PIMC tool “pi” is live on nanoHUB with wiki documentation.
Research
Path Integral Methods
Path integrals allow us to solve physics problems by summing over many over trajectories. This approach is well-suited for problems involving quantum and thermal fluctuations, and it has a smooth crossover to classical physics. The path integrals may be efficiently evaluated with Monte Carlo sampling on modern PC's and high-performance computing clusters. We apply path integral methods to problems in nanoelectronics and quantum chemistry
Quantum Dots
The term “quantum dot” can refer to any structure that exhibits three-dimensional quantum confinement of electrons. We focus our studies on self-assembled heteroepitaxial dots, especially InGaAs/GaAs and Ge/Si. With NSF-CAREER funding we have developed efficient path integral simulations for quantum dots that allow us to calculate equilibrium dot occupation, exciton recombination rates, polarizabilities, and other properties of realistic quantum dot models.
Nanoelectronics
At the nanometer length scale, electronic currents exhibit quantum effects such as quantized conductance and ballistic transport. Through the SRC-NRI SouthWest Institute for Nanoelectronics (SWAN) we are developing new path-intergral simulation techniques to evaluate novel nanoscale switching devices. Our theoretical approach utilizes current-current fluctuations in the framework of Kubo's linear response theory.
Resources
Simulation Tools
As part of our the broader impact of our NSF-CAREER research grant, we develop and distribute open-source simulation tools for modeling quantum dots. These tools are object-oriented and make heavy use of structure XML and HDF5 data formats. We regularly run these simulations on Mac OSX and Linux PC's and high-performance computing centers (ASU's Fulton HPC and UT-Austin's TACC).
Classroom Tutorials
As further outreach, we have ported key parts of our object-oriented path integral simulation code to Java. This classroom demo performs live simulations of sixteen bosons to demonstrate Feynman's path integral model of Bose condensation. At ASU we have used this tutorial to supplement lectures on path integrals in our senior level quantum mechanics and graduate statistical mechanics courses.