Quantum Radar

As the creator of ADS-B : FM closed loop illuminator radar; Roark have long been engaged in the development of Quantum Radar in the microwave domain.

Quantum Radar offers an ideal solution for Roark’s ubiquitous drone detection network given it’s performance against traditional microwave based radar at short distances (<10km). Quantum Radar is particularly effective in detecting “stealth” objects that have low signal reflectivity as well as identifying objects in high noise areas such as EW contested theater and high concentration city deployments. In addition, quantum radar has vastly reduced output radiation compared to traditional radar making it suitable for deployment in populated regions.

How It Works

In traditional radar, a microwave is emitted, when the microwave hits an object, some of the wave is reflected back, this reflection is what gives identification on radar.

For “stealth” devices such as the F35 or B2 bomber their airframes are designed in such a manner to reflect away or absorb the transmitted microwave, that which is returned is so minuscule that it gets lost in the signal noise of the environment. For smaller drones this can be the case almost by accidental design.

Quantum Radar uses a theory known as “quantum entanglement”. This is where a pair of microwave photons are entangled. One of the photons is used as the illuminator and the other stays as the reference point on the radar (known as stored idler photons). The illuminator photon is transmitted and is subsequently reflected back to the radar receiver along with all the other microwaves that make up the “noise”. It is in this noise that a standard radar would lose any of the weak reflectivity from aircraft with a weak radar cross section. As the reflected photon is entangled with the receiver photon, the radar can identify via correlation the reflected photon even in high noise environments and thus identifying the presence of airborne objects including those operating in stealth. The specifics of the aircraft can be further derived via the use of AI/ML models with the training data being the behaviour of the reflected photon.

At present Roark have prototype devices that use entangled pairs of microwave photons at ~5 GHz generated by parametric amplifiers operating at millikelvin temperatures.

It should also be noted that Quantum Radar cannot be jammed as a quantum radar’s receiver is looking for specific quantum correlations that come only from its own transmitted photons. If an adversary floods the radar with regular (un-entangled) radio noise, the quantum radar can effectively ignore it because those signals won’t have the right correlation with the stored idler photons.

Future Works

Roark’s focus is on building portable cryocoolers and multiplexing strategies to enable commercial deployment of Quantum Radar.

Use Cases

Military and Defence

Alongside the detection of stealth aircraft quantum radar could enhance detection across a range of military targets. For instance, it could improve tracking of ballistic missiles and warheads. Intercontinental ballistic missiles (ICBMs) and their warheads travel through space and can release decoys to confuse conventional radars. A quantum radar’s sensitivity and ability to discern real objects from fake (via the quantum signal’s behavior) might help missile defense systems discriminate a genuine warhead from inflatable or metallic decoy balloons during the mid-course phase of flight. The entangled photons’ interaction with a target could even give information on the target’s composition, potentially indicating whether it’s a heavy nuclear warhead or a lightweight decoy. This kind of detailed insight is extremely valuable for strategic defense. Another military use case is submarine detection – while radar is not used underwater, quantum sensing principles might be applied in other spectra (like magnetic sensing or optical ranging through water) to detect submerged vessels. It’s conceivable that a “quantum radar” in the broad sense, perhaps using entangled sonar signals or magnetic field quantum sensors, could one day help reveal stealth submarines that currently elude detection. Similarly, low-observable hypersonic missiles or high-speed drones (which may have small radar signatures and travel in cluttered environments) could be more reliably tracked.

Quantum LiDar

Quantum LiDAR (laser radar) could help autonomous cars navigate in bad weather by better distinguishing obstacles through heavy rain or fog. Oceanographers might use quantum entangled light to improve underwater imaging, since water is a very noisy and absorptive medium for sonar and light – time-correlated photon techniques could enhance seeing through turbulent water or locating objects on the murky seabed.