China claims it has developed a quantum radar that can detect stealth aircraft

[Chakar The Great]

Forward-looking: A quantum radar could be a game-changer on the battlefield, assuming of course that scientists are able to work past the unique hurdles that quantum mechanics present. Effective range and the sheer size of the device, for example, could be limiting factors in terms of practical applications.
State-owned defense specialist China Electronics Technology Group Corporation at the biennial Zhuhai Airshow last week showed off a prototype of what it claims is an advanced quantum radar capable of detecting stealth aircraft.

Traditional radar works by sending out a beam of electromagnetic energy which bounces off an object in its path. The reflected signal is then used to determine the object’s position. “Stealth” aircraft use angular shapes to deflect those signals away from radar equipment or special materials to absorb them, making them appear invisible to radar.


As The Drive explains, a quantum radar more or less does the same thing but uses photons that are “entangled” after a single beam of light is split in half. Only one of the split beams is sent out, the other “stays home.” Thanks to the bizarre behavior of quantum entanglement, the “at home” beam exhibits the same tendencies as the beam sent out which, in theory, would allow the system to observe what happens to the other beam without it having to come back to base.

The group claims it has been working on the technology for years and first tested it in 2015.

Naturally, there are plenty of skeptics. Alan Woodward, a professor of physics at the U.K.’s University of Surrey, told New Scientist that without being able to take the lid off what has been shown, they can’t determine if it is the real deal or an elaborate hoax. It is the Chinese government, after all.

 

[SuvarnaTeja]

Good that India has decided not to buy super expensive stealth fighters and stick with the 4 gen fighters.

 

[Yongpeng Sun-Tastaufen]

Can it detect cloaked things?

 

[Nilgiri]

Its theoretically possible but operationally undeployable imo. The signal processing required would make it so (if you consider whats needed for false target rejection especially). After all any delta in the photons emmited would be reflected in change in state of entangled photons...this could very likely cascade exponentially in relation to computing power available (basically sensitivity tuning would be a nightmare)....given exactly all the things (other than stealthy aircraft) that could cause such a photon change.

This kind of issue has been run into before with other sensors....like thermal scar sensing of submarines. Theoretically submarines indeed do leave a thermal scar on the ocean surface (when surfaced and for some time after) which can be detected....but mass application of this was unfeasible given the long litany of false positives (many things cause thermal scars, some phenomenon of which are still unexplained) that had no relevant way of being processed and filtered out.

@jhungary @gambit @MilSpec @AUSTERLITZ @LeGenD

 

[Chakar The Great]

Its theoretically possible but operationally undeployable imo. The signal processing required would make it so (if you consider whats needed for false target rejection especially). After all any delta in the photons emmited would be reflected in change in state of entangled photons...this could very likely cascade exponentially in relation to computing power available (basically sensitivity tuning would be a nightmare)....given exactly all the things (other than stealthy aircraft) that could cause such a photon change.

This kind of issue has been run into before with other sensors....like thermal scar sensing of submarines. Theoretically submarines indeed do leave a thermal scar on the ocean surface (when surfaced and for some time after) which can be detected....but mass application of this was unfeasible given the long litany of false positives (many things cause thermal scars, some phenomenon of which are still unexplained) that had no relevant way of being processed and filtered out.

@jhungary @gambit @MilSpec @AUSTERLITZ @LeGenD

Its only mater of time, things that seem what you call "undeployable" would be reality in only few years time. Improvements are being made into the system, rectifying the limitations.

 

[Nilgiri]

Its only mater of time, things that seem what you call "undeployable" would be reality in only few years time. Improvements are being made into the system, rectifying the limitations.

I don't deny its potentially possible, but it would need a huge amount of investment over a long period of time, and its very hazy as to the relevancy w.r.t return on investment.

Its just my opinion on it of course from my own experience with systems engineering. There could be some interesting commercial/civilian side that we will see first....but regimented scaleable application to military is whole different matter.

 

[ZeEa5KPul]

Its theoretically possible but operationally undeployable imo. The signal processing required would make it so (if you consider whats needed for false target rejection especially). After all any delta in the photons emmited would be reflected in change in state of entangled photons...this could very likely cascade exponentially in relation to computing power available (basically sensitivity tuning would be a nightmare)....given exactly all the things (other than stealthy aircraft) that could cause such a photon change.

This kind of issue has been run into before with other sensors....like thermal scar sensing of submarines. Theoretically submarines indeed do leave a thermal scar on the ocean surface (when surfaced and for some time after) which can be detected....but mass application of this was unfeasible given the long litany of false positives (many things cause thermal scars, some phenomenon of which are still unexplained) that had no relevant way of being processed and filtered out.

@jhungary @gambit @MilSpec @AUSTERLITZ @LeGenD

Read the paper that launched the field of quantum illumination that this widely misunderstood radar is based on:
https://arxiv.org/abs/0803.2022
It's expected that the signal photons will interact with the environment and destroy the entanglement.

The intuition is that if we send out a signal photon that is entangled with an ancillary photon, then when that photon comes back, if ever, it will prove easier to recognize as the same photon that was sent out. This intuition will turn out to be correct, even though noise and loss completely destroy the entanglement between signal and ancilla.

 

[Nilgiri]

Read the paper that launched the field of quantum illumination that this widely misunderstood radar is based on:
https://arxiv.org/abs/0803.2022
It's expected that the entangled photons will interact with the environment and destroy the entanglement.

Yeah I have read that paper before I think...the issue for me is the scaleability of what they found. That is always where major problems are run into outside of the lab experiments and controlled testing. You have to appreciate effect of multi-input perturbation in the real world imo. Let's see though....there could be research going on certain specific modules to try investigate that....it would be classified though.

 

[Akasa]

What's the point of having a quantum radar?

AESA radars are quite difficult to jam in the first place.

 

[Fawadqasim1]

Its theoretically possible but operationally undeployable imo. The signal processing required would make it so (if you consider whats needed for false target rejection especially). After all any delta in the photons emmited would be reflected in change in state of entangled photons...this could very likely cascade exponentially in relation to computing power available (basically sensitivity tuning would be a nightmare)....given exactly all the things (other than stealthy aircraft) that could cause such a photon change.

This kind of issue has been run into before with other sensors....like thermal scar sensing of submarines. Theoretically submarines indeed do leave a thermal scar on the ocean surface (when surfaced and for some time after) which can be detected....but mass application of this was unfeasible given the long litany of false positives (many things cause thermal scars, some phenomenon of which are still unexplained) that had no relevant way of being processed and filtered out.

@jhungary @gambit @MilSpec @AUSTERLITZ @LeGenD

It will require quantum computers or very large supercomputers

 

[ZeEa5KPul]

What's the point of having a quantum radar?

AESA radars are quite difficult to jam in the first place.

From the abstract of the paper I previously linked:

Quantum illumination with e bits of entanglement increases the effective signal-to-noise ratio of detection and imaging by a factor of 2^e, an exponential improvement over unentangled illumination.

This entails several significant advantages a quantum radar has over a classical radar:

1. The ability to use high frequencies at much longer ranges to detect low RCS targets with sufficient resolution to guide weapons.
2. A jammer/spoofer cannot fool the radar with its own photons since they were never entangled with the radar's signal photons. This gives the radar inherent resistance against all forms of electronic warfare.
3. The ability of the radar to extract exponentially more information from the returning signal means it can be operated at much lower power relative to a classical radar, enhancing the stealth of the radar itself. A stealth fighter might be locked from 400 km away and it would never know it.

If what can be done in the lab can be translated into the field, IADS become completely impregnable. Nothing but throwing overwhelming force and accepting monstrous casualties would work against this, if anything could work at all.

 

[Fawadqasim1]

Good that India has decided not to buy super expensive stealth fighters and stick with the 4 gen fighters.

F 35 is cheaper than your rafale.

 

[SuvarnaTeja]

F 35 is cheaper than your rafale.

• F-35 is more expensive to maintain than Rafale
• India needs to buy F-16 first before F-35 is available after 2030

 

[Akasa]

From the abstract of the paper I previously linked:

This entails several significant advantages a quantum radar has over a classical radar:

1. The ability to use high frequencies at much longer ranges to detect low RCS targets with sufficient resolution to guide weapons.
2. A jammer/spoofer cannot fool the radar with its own photons since they were never entangled with the radar's signal photons. This gives the radar inherent resistance against all forms of electronic warfare.
3. The ability of the radar to extract exponentially more information from the returning signal means it can be operated at much lower power relative to a classical radar, enhancing the stealth of the radar itself. A stealth fighter might be locked from 400 km away and it would never know it.

If what can be done in the lab can be translated into the field, IADS become completely impregnable. Nothing but throwing overwhelming force and accepting monstrous casualties would work against this, if anything could work at all.

Regarding your last point, I think the paper simply meant to say that such systems would be more effective in an EW-heavy environment or in a setting that produces lots of radar clutter. I don't think the abstract specifically mentioned that longer ranges and higher resolutions could be achieved with relatively lower power.

 

[Yongpeng Sun-Tastaufen]

100 years ago there was no radar. Now there is AESA. It's amazing how much tech has advanced in the last 100 years. Who knows what the next decades will bring? One thing is for sure. Quantum radar is coming. And it's coming faster than people expect.