UNSW Led Team Develops Key Device to Advance Quantum Computing Research. (September 27, 2010)

A team led by Andrew Dzurak and Andrea Morello of the Australian Research Council Centre of Excellence for Quantum Computer Technology, School of Electrical Engineering and Telecommunications, University of New South Wales have developed a 'single electron reader', one of the key building blocks needed to make a quantum computer. The team also included members from the University of Melbourne and Aalto University, Finland.

Project leaders Andrea Morello (third from left) and Andrew Dzurak (fourth from left) with their team at UNSW. Credit: UNSW

The abstract, taken from the researchers' paper in Nature, dryly but clearly explains the importance of their contribution to furthering quantum computing:

The size of silicon transistors used in microelectronic devices is shrinking to the level at which quantum effects become important. Although this presents a significant challenge for the further scaling of microprocessors, it provides the potential for radical innovations in the form of spin-based quantum computers and spintronic devices. An electron spin in silicon can represent a well-isolated quantum bit with long coherence times6 because of the weak spin–orbit coupling and the possibility of eliminating nuclear spins from the bulk crystal. However, the control of single electrons in silicon has proved challenging, and so far the observation and manipulation of a single spin has been impossible. Here we report the demonstration of single-shot, time-resolved readout of an electron spin in silicon. This has been performed in a device consisting of implanted phosphorus donors coupled to a metaloxide-semiconductor single-electron transistor — compatible with current microelectronic technology. We observed a spin lifetime of ,6 seconds at a magnetic field of 1.5 tesla, and achieved a spin readout fidelity better than 90 per cent. High-fidelity singleshot spin readout in silicon opens the way to the development of a new generation of quantum computing and spintronic devices, built using the most important material in the semiconductor industry.

Andrew White, Professor of Physics at the University of Queensland, who was not involved in the work, says simply: "This is an outstanding result. The whole world is exploring technologies to build quantum computers, and the hardest approach, but the one with the best information densities, is to implant single phosphorous ions in silicon, and then encode and manipulate information in the spin of those ions. The team have made the key advance of showing they can readout information from these spins in a single fast measurement that faithfully transmits the information. This opens up the road the silicon quantum computing. Their success is the result of literally years of hard work from Australian scientists at the Universities of New South Wales and Melbourne, and it's just wonderful."