CAREER: Terahertz Magnetospectroscopy of Two-Dimensional Systems

University Of Alabama At Birmingham, Birmingham AL

Investigators

Abstract

****NON-TECHNICAL ABSTRACT Current electronics function by controlling the flow of charge in semiconductors in much the same manner that a faucet controls the flow of water. Over the past few decades, electronics have improved their performance (clock speed, power requirements, etc) by progressively getting smaller; today, computer processors have feature sizes that are as small as 32 nm (3.2×10-8 m or about 5000 times thinner than a human hair). As electronics continue to be made smaller, they will soon be governed by quantum mechanical effects that will fundamentally act in different ways than electronics designers are currently accustomed. This research program will study one of these properties, coherence, that will complicate the design of electronics as features continue to shrink. Rather than look at coherence as a problem to be overcome, our research will try to develop the basic tools we will need to exploit coherence for entirely novel electrical applications including quantum computation. We will use lasers to create electronic coherence in high quality semiconductors to learn how to manipulate and control this property. These experiments will develop the basic tools and techniques we need to build an entirely new generation of computers and electronics. This research program will support student education at the undergraduate and graduate levels in this new field of electronics, develop new interactive computer tools to enhance physics education to be made broadly available to all through the Internet, and initiate an outreach program in Alabama to provide a summer optics and photonics program for area incoming high schools. ****TECHNICAL ABSTRACT**** The mitigation and control of coherence in quantum states is an area of great current interest that is critical for the development of the next generation of solid state electronics based on quantum phenomena. We will investigate the terahertz frequency properties of a high mobility (1,000,000 cm2/V/s) gallium arsenide two-dimensional electron gas at cyclotron resonance and the plateau-plateau quantum phase transition in the Quantum Hall limit. These experiments will elucidate the mechanisms and limitations of dephasing in high mobility 2DEG samples and frequency scaling exponents and establish the existence of a universal scaling relationship to investigate the quantum critical point governing this transition. This program will include undergraduate and graduate students in correlated electron materials, high magnetic field research, and ultrafast laser spectroscopy research to train the next generation of scientists in these fields. This program will also initiate an optics summer program for incoming high school freshman beginning in Summer 2012 to increase opportunities for traditionally underrepresented minorities in physics, materials science, and optics.