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The single atom quantum bit Return to case studies page

Professor Andrew Dzurak, Dr Andrea Morello and Phd student Jarryd Pla
Supporting: Frontier technologies
Quantum computers promise to solve complex problems that are currently impossible on even the world’s largest supercomputers.

Data-intensive problems such as cracking modern encryption codes, searching large or complex databases, and modelling biological molecules and drugs would all be easy work for a quantum computer.

In 1998 Dr Bruce Kane, then a postdoctoral researcher at UNSW, published a concept for a quantum computer in the prestigious scientific journal Nature. This accelerated an international race to build a quantum computer – a goal highly prized by researchers around the world since many believe it will be the next significant technological leap in computing technology since the discovery of the semiconductor transistor in 1947. In current computing, information is represented by classical bits, which are always either a 0 or a 1 – the equivalent to a semiconductor transistor device being switched on or off. For quantum computing you need an equivalent, such as the direction that electrons spin around an atom. A clockwise (or “up”) spin would represent a 1 and a counter-clockwise (or downward) spin would represent a 0. These are known as quantum bits, or qubits.

A holy grail would be to make these qubits from silicon as there already exists a trillion dollar silicon industry that can help bring these computers into society.

In 2000, a research centre now known as the Centre for Quantum Computation and Communication Technology (CQC2T) was established at UNSW. This centre positioned Australia at the forefront of the international race to construct a working quantum computer and now has more than 150 researchers in Australia. Between 2000 and 2009 the group has published hundreds of papers on single atom nanotechnologies. Like many such centres, ANFF nodes were established to support their research. The NSW node of ANFF, based at UNSW, specialises in fabrication for high resolution electronics and has been key in keeping CQC2T at the front of the race since 2007. In 2010 ANFF-NSW node director Prof. Andrew Dzurak, and CQC2T project manager Dr Andrea Morello made the first giant leap towards a working silicon quantum computer. They fabricated a device that demonstrated the ability to detect the direction electrons spun around a phosphorous atom – they could read 0 or 1.

The significance of the finding was demonstrated by its publication in “Nature“ and also winning the pair a prestigious Australian Museum “Eureka Prize”. Despite some prior doubt from the greater scientific community, the concept of a silicon based quantum computer was now a reality. However, reading the spin only solves half of the qubit problem. To be useful it also needs a way of setting the spin state, or writing the data. In September 2012, UNSW PhD student Jarryd Pla, his supervisor Dr Morello, and Professor Dzurak published the second giant leap for silicon quantum computing – they learned to write 0 and 1.

“For the first time, we have demonstrated the ability to represent and manipulate data on the spin to form a quantum bit, or ‘qubit’, the basic unit of data for a quantum computer,” says Professor Andrew Dzurak, Director of the NSW node of ANFF at the University of New South Wales. “This really is the key advance towards realising a silicon quantum computer based on single atoms.”

ANFF would like to congratulate Mr Pla, Dr Morello and Prof Dzurak, as well as everyone at CQC2T for their achievements. The global significance of this development has been recognized with Nature once again publishing the group’s research.

Having demonstrated a working qubit in silicon, there is still a long road ahead for the Centre. The next steps will involve combining individual qubits and demonstrating their function as a logic gate, then clustering many of these together to form a chip, the heart of a quantum computer.

Landmark in quantum computing

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ANFF looks forward to supporting CQC2T in their future endeavours in driving the next big leap in computing technology, and seeing it being done from Australian soil.