He explained that QKD essentially leverages two concepts: The Heisenberg Uncertainty Principle, which means that information is encoded onto a laser beam by manipulation at the quantum level, and any attempt to monitor it necessarily disturbs the beam in some detectable way; and the No Cloning Theorem, a law which basically states that it is impossible at the quantum level to make a perfect copy of something. A series of clean up steps also ensures any intercepted information is rendered useless.
"So an eavesdropper could intercept these quantum sets that you are sending but they will never be able to reproduce them perfectly. This is in stark contrast to electronic data, 1s and 0s, which you can copy perfectly as many times as you like," Sharma said.
"Although several groups around the world have quantum cryptographic technology, our group was one of the first in the world to demonstrate the transmission of a completely secret key via bright laser beams and common optics," said Dr Thomas Symul, also part of the research team, in an ANU Newsletter.
Sharma and his group are hoping to commence commercial operations of QuintessenceLabs early next year, and will be pushing a commercial version of their QKD system that will be able to securely transmit unbreakable secret keys over optic fibres.
"Of course interested organisations would include defence, intelligence agencies and various other government departments handling sensitive data. Also tier-one financial institutions, and companies with deep intellectual property like pharmaceutical companies," Sharma said.
In the longer term the technology could be used to relay secret keys all over the world via satellite communications.
Sharma also sees its future potential in personal banking.
"There is billions of dollars in credit card fraud every year. So how do you secure either an Internet or telephone banking transaction?"
He cites recent proposals to couple a mobile phone with a special device that enables quantum transmissions between itself and an Automatic Teller Machine (ATM).
"You have a quantum cryptographic transmission between your mobile and the ATM, and a one-time key which would be downloaded onto your telephone," he said.
"Subsequently you can make an Internet transaction, put in your card number and that one time key can be downloaded via Bluetooth onto your PC. Through the ATM the bank would have a copy of that one time key already, so when you go to use it in an Internet transaction the bank can validate that you are in fact really you."