By Kyle Mizokami
According to the MIT Technology Review, researchers at Austria’s Institute of Science and Technology used entangled microwaves to create the world’s first quantum radar system.
Under a principle known as quantum entanglement, two particles can be linked together regardless of distance, forming what scientists call a quantum entangled pair. When something happens to one particle it can be noticed in the other particle. This in turn leads to a process called quantum illumination, where information about one particle’s environment can be inferred by studying the other particle.
Quantum radars involve pairing photon particles together, shooting one downrange while keeping the second captive for observation. The downrange particle will act in a certain manner as it bounces off certain objects, behavior that can be observed in the captive particle. The result is much more detailed information about the target than seen in previous radars.
Today’s radars can detect targets very well, but provide little detail. Radars can detect an object and note it's altitude, bearing, and distance, but otherwise the target is a big, featureless blob. Air defenders must rely on other things, such identifying radar and other electromagnetic signals emanating from the target, to discern whether the blob is an enemy fighter, bomber, or even a commercial civilian aircraft.
Quantum radars, on the other hand, could provide enough detail for radar systems to identify the object based on physical characteristics. A Su-35 Flanker-E fighter, for example, could be identified by the sweep of its wings, the shape of its nose, and the number of engines.
Another benefit of quantum radars: they emit very little energy and are thus difficult to detect. All contemporary radars emit electromagnetic radiation to detect objects. This radiation makes the radar itself detectable. It’s a lot like having lots of people holding flashlights in a dark room: turning on your flashlight allows you to find other people but the flashlight beam leads straight back to you, giving away your presence and location.
A lack of detectability offers a distinct tactical advantage in warfare. A friendly quantum radar could detect a flight of enemy aircraft without revealing its own presence. This could cause the enemy warplanes to put off defensively jamming local radars and radio signals—which itself is noticeable to the defenders. Their guard down, they could then be ambushed by friendly air defense missiles and fighters waiting for them.
Quantum radars has been billed as a means for detecting stealth aircraft, with claims that it renders efforts to make aircraft invisible to radar useless. According to three experts polled by Engineering and Technology, anti-stealth claims are a “gross oversimplication” and the main advantage of quantum radar is the high definition aspect.