Quantum Radar: Novelty Shift in Subatomic Warfare
Using light to go dark. Quantum illumination may outperform classical radar by 20% and give its architects a major advantage in modern conflict.
America’s stealth warplanes like the F-22 Raptor, F-35 Lightning, and Northrop’s new B-21 Raider can remain more or less invisible on most current-gen radar systems. As mighty as the USAF might be, the flower that is AWACS (advanced warning automatic control system aka radar) has been unparalleled in terms of technological and strategic advances. Research has been conducted on minimizing radio-wave reflections, but finally research has expanded beyond the borders of earth’s radio-wave grid. China finally started its own quantum radar research in 2021. (Don’t forget China conducts quantum research at Canadian universities). Classical radar uses radio waves to determine the distance (ranging), angle (azimuth), and radial velocity of objects relative to the site. It is used to detect and track aircraft, ships, spacecraft, guided missiles, and motor vehicles, and map weather formations, and terrain. Instead of using radio-waves, quantum radar uses light photons produces by microwaves.
Quantum mechanics allows for some very interesting phenomena on the magnitude of the very small. One of these is known as the principle of entanglement, where two particles can be linked together regardless of distance.
This forms what scientists call a quantum entangled pair.
According to the MIT announcement, quantum radars involve pairing photon particles… New research from MIT can prove this technology. The first architects of quantum radar will have their own subatomic fields of geolocation, until sensors can be successfully reverse-engineered.
"We invented a superconducting circuit in 2020 that was able, among other things, to generate entanglement, store and manipulate microwave quantum states and count the number of photons in a microwave field," Benjamin Huard, one of the researchers, told Phys.org. "We then realized that it had all the features we needed to tackle one of the biggest challenges in microwave quantum metrology: demonstrating a quantum advantage in radar sensing."
Researchers create pairs of entangled microwave photons using a superconducting device called a Josephson parametric converter. They beam the first photon, called the signal photon, toward the object of interest and listen for the reflection.In a room temperature environment, this amounts to a background of around 1,000 microwave photons at any instant, and these overwhelm the returning echo. This is why radar systems use powerful transmitters.
Entangled photons overcome this problem. The signal and idler photons are so similar that it is easy to filter out the effects of other photons. So it becomes straightforward to detect the signal photon when it returns.
Of course, entanglement is a fragile property of the quantum world, and the process of reflection destroys it. Nevertheless, the correlation between the signal and idler photons is still strong enough to distinguish them from background noise.
Several past studies tried to develop quantum radars that outperformed conventional radars. This quantum advantage was eventually realized using optical systems, yet before this study it was not yet achieved using microwave radiation.
Huard and his colleagues are now the first who developed a microwave-based quantum radar that performs significantly better than any classical radar technology reported to date. Their radar works by exploiting correlations imprinted between two microwave radiations beyond the bounds of classical physics theories.
"Our radar generates quantum entanglement between a microwave resonator and a signal that is emitted towards a target hidden by a lot of microwave noise such as in the atmosphere," Huard explained. "If the target actually exists, it will reflect a tiny bit of signal together with a lot of noise. Our device then combines this fraction of interesting signal with the field stored in the resonator in a way that produces more or less photons depending on whether the target exists or not. Finally, a built-in microwave photon counter probes these photons."
The implications for stealth technology are massive. Quantum mechanics is finally providing more than new cryptography. Very soon, if not already, USAF aircraft themselves will be “quantum encrypted”.
Keep in mind that quantum radar is a completely new medium. Signals travel through microwave vs. radio-wave mediums. Light against sound.