By Lincoln Parker

In 2017 China achieved what no other country has been able to then or since in quantum communications. In a world-first long distance secure quantum communication, Chinese physicists connected Beijing with Shanghai – a distance of over 1,900 kilometres.

They were able to demonstrate a secure key, distributed using quantum bits of light, or photons, from earth to their satellite and back down to earth. And in another world-first they were able to transmit a video signal encoded from this quantum secure key to make a secure video call from China to Austria.

These two milestones were celebrated worldwide, primarily by scientists, and highlighted to the scientific and military establishments in the US and Europe just how far in front China has developed their quantum technologies.

To understand the importance of these world firsts, we need to know what quantum communication is all about and why it is so special. Quantum communication is an ultra-secure way to communicate or exchange data. To get more technical, it is the ability to send or share particles in an entangled state, carried by single photons of light. These photons cannot be exactly replicated, meaning data transmitted as quantum information cannot by listened in on, nor hacked.

Where does Australia fit into this picture? Australia leads the world in some areas of quantum technologies and I recently sat down with Professor Gavin Brennen, Director of Macquarie University’s Centre for Quantum Engineering, to learn more.

Prof Brennen explains that with advances in quantum computing any and all previously encrypted sensitive communications (from government and military secrets to bank transactions) can potentially be compromised. Optimistic estimates of quantum computer development suggest that achieving this feat could be only about 10 years away, he says.

You might ask why anyone would care if old information or old secrets being hacked really matters? For governments, militaries and corporations it is crucial. ‘Old’ but sensitive information regarding military deployments, installations or locations of missile silos for instance, can still be relevant and help adversaries piece together their intelligence map. Commercial secrets, intellectual property (IP), designs, bank transactions will also all be vulnerable.

Therefore, if you want to ensure your data is robust enough to remain secret then you need a way to communicate that will be secure against future quantum computers. At the moment quantum cryptography is the only proven way to do that, but there is a big push to develop more secure classical codes called post-quantum cryptography, Prof Brennen explains.

Institutions like Macquarie University, along with the University of Technology Sydney, UNSW and Sydney University are leading the way. Government understands the importance of this technology and in March of this year, the then NSW Minister for Innovation Matt Kean backed a proposal for a Sydney Quantum Academy (SQA), which will see researchers from these four universities collaborate to advance quantum technologies (primarily in quantum computing) and link them to industry.

Another area in which Australian research is leading the world is quantum sensing. Among other quantum technologies, an exciting development Prof Brennen and his team are working on is a gravimeter. A gravimeter is a very sensitive sensor which can detect change in the gravitational field – sensing things that cannot be detected via any current sensory system. It is a passive system that probes, not sending out a signal, just receiving the field that is observed by the gravity everywhere around it. A gravimeter will even detect things that don’t emit any kind of electromagnetic signal.

These gravimeters could be deployed on aircraft (or, in the future, satellites) to detect deep underground bunkers, missile silos, or indeed any cavity –without the adversary knowing it has been detected. Prof Brennen explains the gravimeter he is working on “could sense the change in the gravitational field of a human being walking a metre away.”

Note: This article was published by Australian Defence Magazine online and in hard copy in ‘ADM’s Defence Week Premium Edition’. Lincoln Parker works for the NSW Defence Innovation Network (an initiative of the NSW Government, Defence Science & Technology Group and seven NSW universities). The author’s views are his own.

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