Phones and computers a step closer to being more secure


Physicists from the University of Sydney have developed a photonic chip able to communicate information more securely and small enough to fit most computers.

A team from the Centre of Excellence for Ultrahigh bandwidth Devices for Optical Systems (CUDOS) developed the chip for the process of photonic entanglement. Considered the holy grail of long-distance secure communication, photonic entanglement has never before been demonstrated on a chip small enough to fit a computer.

“This development paves the way to explore a new platform for implementing integrated quantum photonic technologies for secure communication on personal phones and computers,” said Dr Chunle Xiong, who led the research, published today in Optica.

The chip exploits the properties of quantum mechanics (entangled photons), the basis for secure networks. Photonic entanglement links the quantum states of photons even if they are sent separately to distant locations.

Changes made to one photon will result in corresponding changes to its partner photon due to the entanglement. This makes it possible to send quantum information without disclosing it to other parties during communication, making transmission secure. Previous demonstrations of this process relied on bulky components unable to be easily integrated with personal phones or computers.

“We demonstrated, for the first time, the time-bin preparation, photon separation and entanglement analysis on a monolithic photonic chip,” said Dr Xiong. “The major challenge is to achieve sophisticated low-loss photonic circuits and device compactness simultaneously. We overcame this by using a silicon nitride photonic circuit, combining the low-loss characteristic of silica and tight integration features of silicon.”
The photonic chip Dr Xiong’s team developed also serves as an entanglement analyser to monitor the security of communications using entangled photons.

CUDOS director and co-author Professor Ben Eggleton said this major breakthrough for quantum technologies is more satisfying because of the collaboration involved.

“It builds on a highly successful collaboration between Physics, and Electrical and Information Engineering at the University of Sydney. We are starting to integrate sophisticated electronics with our photonic circuits, opening the way for many exciting opportunities.”