In the not-too-distant future, electronic devices will approach the size of molecules. Then, says Alex Hamilton, quantum rather than classical physics will be the key to technological advancement.
Hamilton is investigating whether quantum physics can be used to turn conventional electronics on its head. While ordinary devices use electrons to carry the current, his research team is building nano-sized wires that use missing electrons, or ‘holes’, to carry the current instead.
“It’s a bit like when you tilt a spirit level: you can either think of the liquid sinking downwards, or the bubble – the ‘hole’ in the liquid – rising upwards,” he says.
Research groups around the world had been trying to make quantum hole wires for more than a decade when Hamilton’s team reported their success last year.
The idea has generated great excitement because of the unusual quantum properties of holes. While electrons have both electric charge and magnetic spin properties, normally only the charge can be easily controlled. With holes, however, both the charge and spin can be manipulated.
This could revolutionise the way we store and process data, ushering in a new generation of spin-based computers and ‘spintronics’ – high-speed electronic devices that exploit both charge and spin states.
According to Hamilton, spin-based transistors would be smaller, faster and far more energy efficient than the silicon charge-based transistors we use today.
“The first transistors were built in the late 1940s and they’ve given us over half a century of incredible advances,” says Hamilton. “What I envisage now is that we can start to use quantum physics to keep this information revolution going.”
So have the counter-intuitive concepts of the quantum world become commonplace to Hamilton, who is now recognised as a leader in his field? “They still seem slightly crazy,” he says, “you’re never completely comfortable with them. But if you were completely comfortable it would be boring.”