Australian universities create 'photons on demand' optical chip

Breakthrough promises to deliver chips for quantum computing with a length of less than 200 microns.

Research conducted at the University of Sydney has delivered photonic chips that slow down light, creating the ability to produce a single photon of light with increased reliability, which allows for more scalable and smaller optical hardware.

The research is published in the Nature Communications journal, with the team responsible made up of members from Macquarie University, the University of St Andrews, the University of York, and the Australian Research Council Centre of Excellence for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS) based at the University of Sydney, as well as the Australian Defence Science and Technology Organisation (DSTO).

"It is easy for us to generate photons at high rates, but it's much harder to ensure they come out one by one, because photons are gregarious by nature and love to bunch together," said lead author of the research article Matthew Collins, a PhD student at CUDOS.

"For that reason, the quantum science community has been waiting over a decade for a compact optical chip that delivers exactly one photon at a time at very high rates."

An ability to create a single photo in an optical circuit is not new, and has been doable for some time, but the technology has not taken off due to it being error prone, noisy, and slow. This research changes the state of affairs by making it able to combine these "imperfect" sources of photons to create a source of better quality.

"A key breakthrough for this research was the CUDOS development of photonic chips that slow light," said Professor Ben Eggleton, CUDOS director and co-author of the research.

"This makes single photon generation more likely, reducing energy demands and allowing extremely compact devices with lengths no longer than 200 microns, the width of a human hair."

"The smaller these systems are, the more we can fit onto a chip, and the more we can fit onto a chip, the more likely we are to guarantee a single photon when we want it," said co-author associate professor Michael Steel from Macquarie University in Sydney, and CUDOS' science leader for Quantum Integrated Photonics.

Dr Alex Clark, leader of the research team from CUDOS, said that applications for the research would be seen in quantum computing, quantum measurement, and the simulation of biological and chemical systems, as well as applications in secure communications.

"Australia's research in photonic devices is world leading, and we are delighted to collaborate in the area of quantum photonics, which promises revolutionary quantum devices for secure communications," Dr Alexander Zelinsky, chief Defence scientist and head of the DSTO, said.