Electrons line up for quantum computing

University of Wisconsin-Madison scientists have designed a semiconductor-based device that can trap individual electrons and line them up, an advance that could make quantum computing a reality.

University of Wisconsin-Madison scientists have designed a semiconductor-based device that can trap individual electrons and line them up, an advance that could bring quantum computing into the practical realm.

Led by physics professor Mark Eriksson, a team of physicists, materials scientists and engineers have developed a new type of ‘quantum dot’ device for holding electrons that can be scaled up to build a working quantum computer.

Made from tiny amounts of the same semiconductor materials used in today’s computer chips, each quantum dot device is said to contain just one electron. When many of the devices are aligned, the electrons they house become usable quantum bits, or qubits, for computing.

‘The first prerequisite to building a large computer is to have a lot of bits, and we think we have a way to get a lot of them,’ said Eriksson. ‘We’ve done some sophisticated simulations with this device that show the concept is very likely to work, and we’re in the beginning stages of actually making the device.’

Unlike the bits of serial computers, which exist in either the 0 or 1 state, qubits can exist in more than one state at once. This quality frees quantum computers to calculate all the possible solutions to a problem simultaneously, instead of running through them one-by-one like their slower, serial counterparts.

This ability to ‘parallel process’ means quantum computers hold tremendous number-crunching potential for certain tasks that now defy even the most powerful computers.

The team’s device is said to use layers of semiconductor materials and electrostatic forces to squeeze a single electron into place within each quantum dot.

The design reportedly allows the alignment of a large number of dots; their captured electrons separated by a distance only one-one thousandth the width of a human hair.

Eriksson emphasised that researchers worldwide are trying to find the best way to harness subatomic particles for quantum computing and that other researchers have realised success in stringing a few quantum dots together.

‘People often talk about quantum computing in the future tense, but that’s not really right – it exists today. People have solved simple problems with it, but in the future we want to address problems that can’t be solved by any other means,’ says Eriksson.

With its potential for coupling hundreds of electrons, Eriksson believes the team’s device could provide a quantum leap in that direction. ‘Our invention makes it more likely that quantum computing might actually be useful someday instead of a curiosity,’ he added.

A patent on the technology has been filed by the Wisconsin Alumni Research Foundation, a non-profit organisation that manages the intellectual property of the UW-Madison.