Physical Limits to Computation

Exploring the Physical Limits to Computation

Researchers at the University of Notre Dame’s Center for Nano Science and Technology are laying the groundwork for smaller, faster and more efficient electronic devices by exploring how energy is dissipated in nanoscale electron devices and discovering new ways to represent information and perform computation

A multidisciplinary team of electrical engineers, computer scientists, physicists and chemists is developing electronic devices, microsystems and system architecture that can process larger volumes of data—using thousands of times less energy compared to modern information processing systems

"At present there are theoretical and physical limits that define how much energy is required to process digital information (bits) in computing and telecommunication systems," says Alan Seabaugh, professor of electrical engineering, and director of the Notre Dame-based Center for Low Energy System Technology. "How do we enable more energy-efficient computation? Where is energy dissipated, and why? What is the simplest and most cost-effective way to build a computing engine?"

These key questions are guiding development of innovative semiconductor switching technologies such as quantum mechanical tunneling, an energy transport process that becomes exponentially more efficient as the energy barriers in devices are reduced to the nanometer scale. Innovative methods of electronically controlling the tunneling process are at the core of the low-voltage, low-power tunnel transistors being designed at Notre Dame. 

Notre Dame engineers also are discovering new ways to represent and process information using nanomagnetic logic devices. 

"These chips use polarization to represent digital information in a magnetic material," says Michael Niemier, assistant professor of computer science and engineering. "The computation and signal transmission are achieved through the interaction of magnetic fields at the nanoscale, instead of with charge."

The theory, design, development and testing of these devices is being explored at the Center for Nano Science and Technology, utilizing the center’s new nanofabrication facility, a state-of-the-art clean room in the Stinson-Remick Hall of Engineering. 

The huge gains in computational power and energy efficiency that appear to be possible at the nanoscale promise lower energy costs, better communications and superior ability to process large volumes of data, and open up a wide array of new applications in healthcare and environmental protection. This new energy-efficient computing technology will lead to processors capable of handling much more complex problems, such as global climate change, weather prediction, nuclear fusion and the behavior of new materials and devices. More energy-efficient, environmentally friendly and cost-effective technologies are becoming essential to the development of electronics that will enable the continued and sustainable development of life in harmony with the environment.