Researchers achieve record 10-fold stability for quantum computers

18 Oct 2016

Chaotic lights. Image: Roman Sigaev/Shutterstock

A team of researchers has achieved unprecedented stability for quantum computers, 10 times that of any previously built device.

The dawn of a quantum computer age appears to be upon us. New developments occur year-on-year, in the hope of one day being able to run calculations that far outstrip those of current silicon chip computers.

Rather than being based on a binary system of ones and zeros represented as bits, quantum computers use quantum bits (qubits) that can be one, zero or both, resulting in incredibly fast processing power.

Now, a team from the University of New South Wales in Australia has published a paper in Nature Nanotechnology that shows it has achieved unparalleled stability within its own quantum computer.

Based on its findings, the team created a new qubit that remains in a stable superposition for 10 times longer than previously achieved, dramatically expanding the time during which calculations could be performed in a future silicon quantum computer.

This new qubit is referred to as a ‘dressed qubit’ because the single atom is contained within silicon and merged with an electromagnetic field.

Quantum computer diagram

Artist’s impression of a single-atom electron spin, hosted in a silicon crystal and dressed by an oscillating electromagnetic field. Image: Arne Laucht/UNSW

Can be used with today’s computers

This results in the qubit storing quantum information much longer than an ‘undressed qubit’, which could hopefully result in more stable and powerful quantum computers in the future.

“This new ‘dressed qubit’ can be controlled in a variety of ways that would be impractical with an ‘undressed qubit’,” said Andrea Morello, leader of the research team.

“For example, it can be controlled by simply modulating the frequency of the microwave field, just like in an FM radio. The ‘undressed qubit’ instead requires turning the amplitude of the control fields on and off, like an AM radio.

“In some sense, this is why the dressed qubit is more immune to noise: the quantum information is controlled by the frequency, which is rock solid, whereas the amplitude can be more easily affected by external noise.”

What makes this development practical in the short term is that because the device is built upon standard silicon technology, powerful and reliable quantum processors can be built on the same fabrication process already used for today’s computers.

Colm Gorey was a senior journalist with Silicon Republic