Atom transistor to speed up computers

An international team of scientists have created a tiny transistor that could one day help quantum computers process impossibly large amounts of information.

The researchers are the first to make a transistor's electrical current pass though a single atom in a controllable way, another step towards the quantum computer chip.

Their research is published online in the journal Nano Letters.

Powerful computers

Although still a couple of decades away, quantum computers have the potential to solve calculations faster than all current computers working at once, says one of the research leaders, Professor Andrew Dzurak of the University of New South Wales.

"They could revolutionise society by doing things like developing more accurate climate change models and predicting how new medicines will work, reducing the time needed for lengthy lab experiments".

But in order to create these computers, researchers first need to develop quantum units of information called 'qubits' - and this can only be done with single-atom transistors.

The research team, involving scientists from the University of Melbourne, the University of New South Wales and Helinski University of Technology in Finland, are the first to successfully create these tiny devices on a silicon computer chip.

Quantum tunnelling

Scientists have struggled to create single-atom transistors until now because it's extremely difficult to control the placement of atoms at such a small scale, according to Dzurak.

"Transistors work almost like a sink - electrons pass like water from a source electrode to a drain electrode - and there's a gate that turns the flow on and off," he says.

By placing the single atom close enough to the source and drain, the team made electrons pass through it in a controllable way using a phenomenon known as quantum mechanical tunnelling.

The chance of this quantum mechanical effect occurring on a large scale is almost impossible, but at a nano-scale it's common and results in an object at the edge of a barrier suddenly passing to the other side, explains Dzurak.