Research

1. Materials Computation Center, University of Illinois Duane D. Johnson and Richard Martin, NSF DMR-03-25939Spintronics in Triple Quantum Dots J.P. Leburton (ECE) and R.M. Martin (Physics) Research Objectives: Understand many-body effects in semiconductor quantum dots (QDs) for applications in quantum information processing. Approach: We concentrate on material and design parameters that influence the exchange interaction between conduction electrons in realistic double QDs. For this purpose, we use a combined approach based on density functional theory (DFT) to model the QD potential, and diffusion quantum Monte Carlo to simulate accurately exchange and correlation of electrons in the QD. Significant Results: We investigate quantum structures designed for three linearly coupled vertical QDs made by lithography techniques (artificial “molecules” in analogy with CO2 or NH2 linear molecules). DFT calculations unable us to obtain the total energy of the system for a few electrons, the single electron charging point (circles on bottom left) and the stable spin configuration for N=2-4 electrons (bottom right) Broader Impact: Controlled device design through science, and cross-disciplinary trained students for industry. STM image of three linearly coupled QD device. Left: Total energy for N-electrons; right: Spin configuration x 10-3 N = 1 N = 2 N = 3 N = 4 J. Kim, P. Matagne, J.P. Leburton, R.M. Martin and S. Tarucha “ Engineering Quantum Confinement and Orbital Coupling in Laterally-Coupled Vertical Quantum Dots for Spintronic Applications” IEEE Trans. Nanotechnol. (in review)