A UNSW-led research team has encoded quantum information in silicon using simple electrical pulses for the first time.
Lead researcher, UNSW Associate Professor Andrea Morello from the School of Electrical Engineering and Telecommunications, said his team had successfully realised a new control method for future quantum computers.
The findings, a vital step towards making an affordable large-scale quantum computer, were published today in the open-access journal Science Advances.
Unlike conventional computers that store data on transistors and hard drives, quantum computers encode data in the quantum states of microscopic objects called qubits.
Morello said the method works by distorting the shape of the electron cloud attached to the atom, using a very localised electric field.
“This distortion at the atomic level has the effect of modifying the frequency at which the electron responds, he said.
“Therefore, we can selectively choose which qubit to operate. It’s a bit like selecting which radio station we tune to, by turning a simple knob. Here, the ‘knob’ is the voltage applied to a small electrode placed above the atom.”
“The findings suggest that it would be possible to locally control individual qubits with electric fields in a large-scale quantum computer using only inexpensive voltage generators, rather than the expensive high-frequency microwave sources.”
The UNSW team, which is affiliated with the ARC Centre of Excellence for Quantum Computation & Communication Technology, was first in the world to demonstrate single-atom spin qubits in silicon, reported in Nature in 2012 and 2013.
The team has already improved the control of these qubits to an accuracy of above 99% and established the world record for how long quantum information can be stored in the solid state, as published in Nature Nanotechnology in 2014.