A revolutionary computer chip made of ultra-small magnets that holds the promise of almost
unimaginable speed and power came a step closer to reality thanks to a recent Notre Dame
breakthrough.
Notre Dame electrical engineering researchers Alexandra Imre, Lili Ji, Gary Bernstein
and Wolfgang Porod, along with Gyorgy Csaba of the Technical University of Munich,
demonstrated that submicroscopic magnets, billionths of a meter in size, can perform the
function of transistors in a logic circuit, the basis of all computing functions.
The Notre Dame group adapted the "nanomagnets" to an approach known as Quantum
Dot Cellular Automata (QCA) previously invented by Porod and Craig Lent, Freimann
professors of electrical engineering.
In QCA, an electron is confined in a structure known as a quantum dot, which can be
arranged into cells. Those cells can be arrayed to form switches, wires and computer logic
devices. "The basic idea [for the magnetic version] is the same as for the original electronic
QCA," Porod says, "except that nanomagnets hold the information and magnetic interactions are
used to perform logic."
The QCA system holds the promise of immense power and speed because as many as one
trillion devices can be placed on a one-centimeter chip compared to six million in today's state-of-the-art chip. Also, unlike conventional microprocessors, nanomagnetic QCA chips could be
easily reconfigured to maximize efficiency even after installation in a computer; additionally,
they would retain information after power is cut off.
(July 2006)
