Researchers at the University of Waterloo are using the quantum principle of entanglement – memorably called “spooky action at a distance” by Albert Einstein – to develop a quantum radar that can expose stealth aircraft and missiles.

Unjammable radar

Traditional radar is vulnerable to interference from space weather events such as geomagnetic storms and solar flares, making it harder for this technology to reliably identify objects.

For their part, stealth aircraft use special paint and body design to absorb and deflect radio waves, and electronic jamming is used to swamp detectors with artificial noise, making these aircraft invisible to normal radar.

To overcome these problems of its traditional predecessor, quantum radar uses a sensing technique called ‘quantum illumination’, allowing it not only to cut through noise but also to identify objects designed to avoid detection.

At its core, quantum radar leverages the principle of ‘quantum entanglement’, which describes the phenomenon of two photons forming a connected or entangled pair.

Leveraging this principle, quantum radar sends one photon in an entangled pair to a distant object and keeps the other. Photons in the return signal are then checked for specific entanglement signatures while all others are discarded, greatly improving the radar signal-to-noise ratio in noisy environments.

New sources of entanglement

For quantum radar to work in the field, researchers must come up with a fast, on-demand source of entangled photons at the click of a button,” says Jonathan Baugh, a faculty member of the University’s Institute of Quantum Computing.

As yet, quantum illumination has only been explored in the laboratory environment, but defence programmes may need it to be field ready soon. To this end, the Canadian government, under the Department of National Defence’s All Domain Situational Awareness (ADSA) Science & Technology programme, is investing $2.7 million to expedite its use in the field.

In addition, the 54 North Warning System (NWS) radar stations, based in the Arctic and operated by the North American Aerospace Defence Command (NORAD), are nearing the end of their life spans and may need to be replaced as early as 2025. The potential of quantum radar to detect stealth aircraft and beat electronic jamming makes it an obvious technology of interest for such radar system replacement, if an industrialised solution can be perfected within a reasonable time.

“Our project will allow us to develop the technology to help move quantum radar from the lab to the field,” said Baugh. “It could change the way we think about national security.”