A real-time quantum encryption system can be deployed onto existing networks to secure communications in the banking and finance industries and for critical applications, says University of the Witwatersrand (Wits) School of Physics’ Professor Andrew Forbes.
Forbes and his team, along with physicists from Heriot-Watt University, in Scotland, led by Professor Jonathan Leach, published an article in science in journal Nature Communications last month in which they demonstrated entanglement swapping between photons and the teleportation of orbital angular momentum (OAM) patterns of light.
“This is accomplished by interfering two photons from independent entangled pairs, resulting in the remaining two photons becoming entangled,” Forbes explains.
This process results in establishing entanglement between two distant points without requiring a photon to travel the entire distance, thus reducing the effects of decay and loss. It also means that line of sight between the two points is not required.
“The information of one photon can be transferred to the other – a process called teleportation.”
While the scientists have demonstrated the potential for and are developing systems that use hundreds of entangled photons to communicate information across a virtual link, another use of the technology is to make conventional fibre-optic communications inherently secure by using quantum encryption, Forbes highlights.
“The laws that govern quantum physics can be used to distribute quantum keys between nodes in the network and in real time. Owing to the phenomenon that entangled pairs of particles register changes made to one of the particles in the pairs, the entangled pairs can also be used as quantum encryption keys that are inherently securely distributed,” he says.
Any attempt to interfere with the entangled pairs will cause the pairs of photons to disentangle, leading to a loss of information and synchronisation. This will also alert the network operators to the failed cyberattack.
“All the network elements and infrastructure can remain. Our quantum encryption system will be deployed at key nodes in the network on the transmitters and receivers. It will then synchronise the pulses on the fibre-optic network and encrypt the signals in real time. The quantum signatures, which function as encryption keys, are generated continuously and distributed instantaneously,” says Forbes.
Further, as the encryption of the communications is quantum-based, rather than digital, the processing power required for encryption and decryption is reduced.
The technology uses the OAM patterns of the photons as a high-dimensional alphabet with which to communicate information between entangled pairs. The working prototype at the Wits School of Physics can differentiate between 200 patterns simultaneously. Forbes believes this can easily be increased to 1 000 patterns, and even more, for commercial applications.
Additionally, Forbes notes that the large range of OAM patterns of photons can be leveraged to increase the amount of information that can be sent along fibre-optic networks. Because the patterns are orthogonal to one another, they do not interfere with other signals and this allows for the multiplexing of signals to increase the bandwidth of the network.
“The physical principles have been demonstrated and the technology can readily be scaled for commercial applications, and key industries will aim to use quantum encryption to secure their fibre-optic communications,” he states.
The scientists are investigating various commercialisation models for the technology, including a licensing model, a direct commercial partnership or a standalone spin-off company.