CHINA claims it has a radical new ‘quantum’ radar capable of detecting stealth fighters at great distances.


Staff member
Does this mean our ultra-expensive new F-35 is obsolete, even before we get it?
The RAAF’s first F-35’s will be making their debut Australian appearance at the Avalon air show this week. It’s not a combat-capable aircraft, yet, though the first partially operational US squadron of the type was deployed to Japan earlier this year.
But Beijing state media has boasted its scientists have successfully tested a new type of radar capable of defeating stealth technology at ranges out to 100km.
The new sensor technology uses concepts on the edge of our scientific understanding.
And a Chinese state-owned technology group late last year declared it had mastered it.
The new technology had “important military application values” because it could identify aircraft and ships “invisible” to conventional radar systems, a press statement read.
Understanding that technology exposes its full potential.
A photon is a particle with wavelike properties that carries energy without mass. We usually hear of it in terms of light, but it is the basis of all electromagnetic radiation.
Where radar sends out a beam of photons as radio waves, quantum radar uses entangled photons.
Put simply, entangled photons are two separate photons that share a deep quantum link. The upshot is the photons mirror each other’s behaviour when one of them is influenced in some way.
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In terms of radar, a crystal can be used to ‘split’ such entangled photons and cast one into the sky.
For a time at least, the twin photons retain their ‘spooky’ link — mirroring the same responses to the environment the other encounters.
It’s a quirk of quantum physics which strained the understanding of Albert Einstein when he grappled with the idea in the 1930s.
Quantum radar would send out bursts of photons while retaining their ‘pairs’. The changes in behaviour of the retained photon would then reveal what’s happening to the photon in the beam.
Ultimately, the point is the same: the entangled photons bounce back to a sensor which can then compute course, speed and size.
But the use of tangled photons has a second major benefit over radio waves.
It’s not likely to be jammed.

Where modern composites can ‘trap’ radio waves within their molecular structure, whatever happens to an entangled photon would be replicated — and measured — in its paired mate back at the radar site.
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And different materials affect protons in different ways.
Because of this, analysts say quantum radar could ultimately be capable of determining what an aircraft is made of — or even carrying.
At one level this would eliminate the effectiveness of decoys. At another, it could identify which aircraft — or missile — is carrying nuclear warheads.
And, unlike existing radar, their transmissions would not be detectable.
Any stealth aircraft would not know it had been ‘seen’.
Despite the ominous sounding properties of this unbeatable radar, the foibles of quantum mechanics make the actual exploitation of such technology incredibly difficult.
Photon pairs degrade. The longer one photon remains in the outside environment, the more stress is placed on the link with its partner. It’s called quantum decoherence.
This has implications for a quantum radar’s maximum range: keeping the photons paired for the time it takes one to cover 100km represents an enormous technical challenge.