Quantum vision

Physicists from the Australian National University explain their progress in optical quantum computing.
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20 September 2016

As Australian researchers make progress in creating a quantum computer, the Australian Government is ramping up its support for the potentially disruptive new technology.

A most recent research development includes a paper published in Nature Physics. There physicists from the ARC Centre for Quantum Computation and Communication Technology (CQC2T) facility at the Australian National University (ANU) describe a trap for photons created by shining infrared lasers into ultra-cold atomic vapour.

Coralling photons in such a cloud of ultra-cold atoms promotes interaction between photons, which usually just pass each other at the speed of light.

According to lead researcher Jese Everett from the ARC Centre of Excellence for Quantum Computation and Communication Technology, being able to control the movement of light is a major step towards developing optical quantum computers.

The researchers are working towards one single photon changing the phase of another. This would make it possible that units of quantum information , called qubits, exchange information, and thus create a quantum logic gate, the building block of quantum computers.

While the technology is still a long way off from becoming reality, its potential is significant.

Quantum computers based on photons could connect easily with communication technology such as optic fibres and have potential applications in fields such as medicine, defence, telecommunications and financial services.

Meanwhile the Australian Government is betting $25 million on a different approach.

The investment contributes to a $70 million development of a prototype silicon quantum integrated circuit - the first step in building a functional quantum computer.

The project is backed by a consortium that also includes the University of New South Wales ($25 million), the Commonwealth Bank ($10 million), and Telstra ($10 million).

It is led by UNSW Professor Michelle Simmons, who is the director of the CQC2T and has spearheaded the use of silicon as a physical basis for quantum computers.

Significant progress has been made, including a paper published in the journal Nature in 2015 describing the world's first quantum logic gate performed in silicon.

Artist’s impression of the two-qubit logic gate device developed at UNSW. Each electron qubit (red and blue in the image) has a ‘spin’, or magnetic field, indicated by the arrows. Metal electrodes on the surface are used to manipulate the qubits, which interact to create an ‘entangled’ quantum state. Credit: Tony Melov/UNSW.

The work by UNSW Professor Andrew Dzurak's team and co-workers demonstrated calculations between two qubits, and this cleared a final hurdle for the development of a silicon based quantum computer.

According to the researchers, the key advantage of using silicon to create a quantum circuitry is that silicon is also used in existing computer chips, which should make it easier to manufacture a full-scale processor chip.

The Australian Research Council has recently extended its funding of the CQC2T, at a cost of $34 million.