The Coherent Nonlinear Optical Response and Control of Single Quantum Dots

Abstract

Abstract : Work on this program is aimed at developing and understanding nano-optical structures with emphasis on developing quantum optical-based devices. Specific work focused on semiconductor quantum dots. The major achievements include the first demonstration of an all optically driven quantum NOT-gate based on using the exciton-Bloch vector as the qubit (Science 2003). We also demonstrated optical density matrix tomography on this system. Since the fast recombination time of quantum dot excitons may limit these systems for quantum information applications, we initiated experiments on negatively charged quantum dots (similar to ions) where for quantum information processing, the qubit would be the electron spin. The energy level structure in this system is a 3-level A-system, which is also of importance to novel coherent optical applications such as slow light and electromagnetic induced transparency. Our experiments in this system are just beginning, but we have successfully demonstrated optically induced coherence in this system, the unexpected effect of spontaneously generated spin coherence, and coherent optical control. A summary of our work leading up to this was published by invitation in Physics Today while the achievement of the quantum NOT-gate was reviewed in Photonics News.