Ultrafast Optical Studies of Semiconductor Materials for Spintronics and Quantum Computing

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The research program supported by this Discovery Grant involves the study and control of fast processes in novel semiconductor materials that have strong potential for applications in advanced technology (magneto-sensitive logic, opto-electronics and quantum information). Our experiments all utilize special lasers that produce short pulses of light with a duration of about 100 femtoseconds. In order to put this time scale into perspective, comparing 100 femtoseconds to 1 second is equivalent to comparing 1 centimeter to the distance between the earth and the sun. These so-called ultrafast laser pulses may be used to study extremely rapid events, such as the motion of electrons in solids. The primary objective of our research is the pursuit of ultrafast optical control in two classes of materials: (i) diluted magnetic semiconductors; and (ii) semiconductor quantum dots. Diluted magnetic semiconductors are traditional semiconductors doped with magnetic atoms. These materials may change the way we build computers, allowing logic and memory functions to be combined as well as the incorporation of optical interconnects and switching, leading to computers with lower power consumption and higher speed. Our group is using ultrafast laser techniques to develop optically-addressable magnetic memory elements based on these materials. Semiconductor quantum dots are tiny (nanometer-sized) regions of one type of semiconductor inside a 3D matrix of another semiconductor. These tiny regions (the dots) may be used to trap individual electrons and act as "quantum bits" in a solid state quantum computer, promising advances in high power computing, cryptography, and many other important areas. The use of ultrafast pulses for computation, one of the goals of our research, would make such a computer extremely fast and allow computations to be carried out before decoherence (which destroys the quantum information) sets in. Through the development of a broad-based foundation of knowledge in these cutting-edge areas of science and technology, together with the training of highly-skilled researchers for the photonics and semiconductor industries, the proposed research program will have valuable and lasting benefits to Canada.