25 August 2021

Quantum radar draws ever closer

Quantum radar provides a better image of an object, at the same time as it reduces the risk that the operator or platform doing the spotting will be detected. FOI is following developments on behalf of the Swedish Ministry of Defence.


The image shows “squeezing.” Squeezing creates entanglement.

The development of quantum computers has achieved a breakthrough that has brought the technology closer to practical application. For example, a quantum computer created by Google has performed a calculation of such complexity that ordinary computers would have taken decades to complete it. The arrival of quantum computers is a prelude to other products. One of these is quantum radar. In 2019, news from Canada and Austria, among others, announced that researchers had created quantum radar systems. The systems function much as traditional radars, but with improved characteristics.

“Among other things, you see what is depicted a little better, at the same time as quantum radar uses a weaker signal, which decreases the risk of detection. It is also considered to work better in distorted environments and it is believed that in future the technology will be able to indicate which material the object in the image is made of,” says Magnus Höijer, Deputy Research Director at FOI, who with co-authors Tommy Hult and Per Jonsson wrote the report, Quantum Radar: The Follow-up Story, for the Swedish Armed Forces.

Less risk of detection

After an initial period when these successes were partially questioned, news has begun streaming in again, for example from the University of Waterloo, Canada.

“Research there shows that with quantum radar you get a strong correlation with what is imaged. The images have been generated using a signal that is only one-eighth as strong as in traditional radar, which drastically reduces the risk of detection,” says Magnus Höijer.

One of the reasons that quantum radar is being followed with such excitement in military circles is that it is both hoped and feared that the technology will be able to reveal “invisible” stealth aircraft.

“It’s not impossible, even if we at FOI are doubtful, since earlier information that the system can detect invisible aircraft relies on faulty reasoning,” says Magnus Höijer.

Several countries active

China is the only country in the world who claims to have a functioning quantum radar in use, something the rest of the world doubts. But Magnus Höijer maintains that it will not be long before useable quantum radar is available; in addition to China, countries such as the United States, Canada, Germany and the United Kingdom are active.

“Only five years ago, most researchers would have said that quantum radar is a technology that we won’t see within our lifetimes. Now, I believe we’ll have the technology within ten years. I would now say that it mostly depends on how much money is invested,” says Magnus Höijer.

FOI, with its radar research of world class, is following developments within both quantum computing and quantum radar.

“So far, we’re working on our own. However, several research calls have been announced within European defence research, but if we’re going to be part of such a project it will require that we have our own knowledge to contribute,” says Magnus Höijer.

Great importance

Quantum computing is going to change the world. Magnus Höijer describes its development as so powerful that he would compare it to telling a person in the 1800s that you could produce electricity in a river in Norrland, in northern Sweden, and send it down to the southernmost part of the country. Development is being carried out primarily in the civilian sector.

“But this is going to lead to military applications, not only quantum radar but also better sensors and so on. Small improvements are important in military activities: if you can see just a little bit farther, a little better and find out just a little more about what you’re seeing, it can have major significance.”

  • Provides a better image of what is to be imaged.
  • Uses a weaker signal. This lessens the risk of detection.
  • Functions better in electromagnetically distorted environments.
  • It is expected to be able to say which material an imaged object is made of. This can reveal where the object comes from.