The end of stealth ? maybe, quantum radar.

[PRTVR]

Came across this on YouTube, if correct there will be less need for stealth aircraft.
https://youtu.be/Db_-ftpoMm4

[spikep]

To the best of my knowledge, it won’t overcome stealth.
Apparently the quality of the return signal is so good that it can identify what the aircraft is. Presently you only get a blob and therefore need other means of identifying who it is, ie, IFF/SSR (secondary radar). These won’t be needed with quantum radars.

The second advantage is that the signal is so small, the target will not know you have picked them up. I’m military terms your radar warning receiver won’t tell you that the enemy know where you are. Obviously this is not good for the pilot who may find a missile coming at them.

[Krikkit]

spikep said:

To the best of my knowledge, it won’t overcome stealth.

Correct, although you may end up with radar sensitive enough that it's practically impossible to create something that flies well enough to be useful and not defeat the radars.

Ultimately it's a step change in the stealth vs radar hundred billion dollar game.

[anonymous-user]

Ok, so two particles are entangled (in the quantum sense) one fired out towards an oncoming aircraft, the other kept in the radar itself, and the quantum state of the remote particle is of course reflected instantaneously in the state of the local particle. But what state does the remote particle find itself in, and how is that changed by passing through an aircraft? The particle is passing through our atmosphere all the time, and yes, an aircraft is much more dense, but in terms of the free space in an atom, density on a human scale is almost irrelevant?

[PRTVR]

I came across this, maybe a bit clearer in explanation.
https://hackaday.com/2019/08/26/quantum-radar-hide...
It looks like the Chinese may have one working to detect underground structures.

Edit to add it's magic.

Edited by PRTVR on Monday 7th October 12:05

[anonymous-user]

ok, so it's using the entanglement as a flag to increase the SNR for the system, in effect, that flag allows it to see which of the particles collected by the detector are ones it originally sent out, vs which are just "Background" particles that happened to get swept up by the detector. When a reflected particle is interrogated by the detector, the state of its entangled 'reference' particle also changes, whereas a background particle detection causes no state change in the reference.

And whilst that does indeed allow for a significant boost in SNR from any given beam power, it certainly doesn't preclude in anyway against stealth as far as i can imagine?

(and the system resolution is still necessarily bound by the fundamental wavelength of the beam in both the physical and time domains as normal)

[PRTVR]

Max_Torque said:

ok, so it's using the entanglement as a flag to increase the SNR for the system, in effect, that flag allows it to see which of the particles collected by the detector are ones it originally sent out, vs which are just "Background" particles that happened to get swept up by the detector. When a reflected particle is interrogated by the detector, the state of its entangled 'reference' particle also changes, whereas a background particle detection causes no state change in the reference.

And whilst that does indeed allow for a significant boost in SNR from any given beam power, it certainly doesn't preclude in anyway against stealth as far as i can imagine?

(and the system resolution is still necessarily bound by the fundamental wavelength of the beam in both the physical and time domains as normal)

As I understand it stealth is possible due to the reduction in returns from the aircraft compared to a normal aircraft, if you do not need a return signal, just to strike the aircraft to get detection ,it matters not the shape or design of the aircraft.

[anonymous-user]

PRTVR said:

Max_Torque said:

ok, so it's using the entanglement as a flag to increase the SNR for the system, in effect, that flag allows it to see which of the particles collected by the detector are ones it originally sent out, vs which are just "Background" particles that happened to get swept up by the detector. When a reflected particle is interrogated by the detector, the state of its entangled 'reference' particle also changes, whereas a background particle detection causes no state change in the reference.

And whilst that does indeed allow for a significant boost in SNR from any given beam power, it certainly doesn't preclude in anyway against stealth as far as i can imagine?

(and the system resolution is still necessarily bound by the fundamental wavelength of the beam in both the physical and time domains as normal)

As I understand it stealth is possible due to the reduction in returns from the aircraft compared to a normal aircraft, if you do not need a return signal, just to strike the aircraft to get detection ,it matters not the shape or design of the aircraft.

This quantum system, as it is current explained, still needs a reflected return of the beam emitted. The difference is that because quantum entanglement is used as a "flag" to identify the returned signal from the chaos of the normal background signal the systems transmission power can be many times less than for a conventional radar (which must get enough signal back in order to pick out that signal from the background by amplitude alone)

[Atmospheric]

[AshVX220]

Max_Torque said:

PRTVR said:

Max_Torque said:

ok, so it's using the entanglement as a flag to increase the SNR for the system, in effect, that flag allows it to see which of the particles collected by the detector are ones it originally sent out, vs which are just "Background" particles that happened to get swept up by the detector. When a reflected particle is interrogated by the detector, the state of its entangled 'reference' particle also changes, whereas a background particle detection causes no state change in the reference.

And whilst that does indeed allow for a significant boost in SNR from any given beam power, it certainly doesn't preclude in anyway against stealth as far as i can imagine?

(and the system resolution is still necessarily bound by the fundamental wavelength of the beam in both the physical and time domains as normal)

As I understand it stealth is possible due to the reduction in returns from the aircraft compared to a normal aircraft, if you do not need a return signal, just to strike the aircraft to get detection ,it matters not the shape or design of the aircraft.

This quantum system, as it is current explained, still needs a reflected return of the beam emitted. The difference is that because quantum entanglement is used as a "flag" to identify the returned signal from the chaos of the normal background signal the systems transmission power can be many times less than for a conventional radar (which must get enough signal back in order to pick out that signal from the background by amplitude alone)

From what I saw on the video and my very limited knowledge, what Prof Simon is saying is that there is no return signal. The detection is there because the retain particle changes, indicating that the transmitted particle has changed. So, no actual return signal as we would understand it?

[Chuck328]

Nothing to see here.

At least according to a friend who works for Leonardo (formally Selex Galileo, formally BAE Systems).There a few bits to it but it's all theoretical says he. Given this this kind of stuff is their back yard, I'll go with that.

Who knows though, maybe someone has cracked it.

[anonymous-user]

AshVX220 said:

From what I saw on the video and my very limited knowledge, what Prof Simon is saying is that there is no return signal. The detection is there because the retain particle changes, indicating that the transmitted particle has changed. So, no actual return signal as we would understand it?

But the transmitted particle is only changed by its state being "read". It isn't changed by hitting the target. I think it's an SNR boosting technicque, where say 1 million particles are received back into the detector in a given time period, of which 999,999 are background radiation, and one is a reflected particle bounced back from the target. Normally, that one particle is "lost", effectively swamped by the background particles. However, thanks to quantum coupling, when the one particle that has been bounced back is received, and "read" by the receiver, then the state of it's matching particle in the local storage also changes, and if you monitor those changes, you effectively discretise your receiver, massively boost the SNR, and mean you can pick the "data" out from the background?

[AshVX220]

Max_Torque said:

AshVX220 said:

From what I saw on the video and my very limited knowledge, what Prof Simon is saying is that there is no return signal. The detection is there because the retain particle changes, indicating that the transmitted particle has changed. So, no actual return signal as we would understand it?

But the transmitted particle is only changed by its state being "read". It isn't changed by hitting the target. I think it's an SNR boosting technicque, where say 1 million particles are received back into the detector in a given time period, of which 999,999 are background radiation, and one is a reflected particle bounced back from the target. Normally, that one particle is "lost", effectively swamped by the background particles. However, thanks to quantum coupling, when the one particle that has been bounced back is received, and "read" by the receiver, then the state of it's matching particle in the local storage also changes, and if you monitor those changes, you effectively discretise your receiver, massively boost the SNR, and mean you can pick the "data" out from the background?

I clearly don't understand it then. I thought you send out a bunch of particles, which are paired to particles you retain. When the "sent particles hit something which alters their spin, the spin in the retained particle changes indicating that the "sent" particle hit something. Not a reflected/returned particle detection.
This is clearly way above my head and I work in defence and did radar detection and analysis in the RN. LOL

[PRTVR]

AshVX220 said:

Max_Torque said:

AshVX220 said:

From what I saw on the video and my very limited knowledge, what Prof Simon is saying is that there is no return signal. The detection is there because the retain particle changes, indicating that the transmitted particle has changed. So, no actual return signal as we would understand it?

But the transmitted particle is only changed by its state being "read". It isn't changed by hitting the target. I think it's an SNR boosting technicque, where say 1 million particles are received back into the detector in a given time period, of which 999,999 are background radiation, and one is a reflected particle bounced back from the target. Normally, that one particle is "lost", effectively swamped by the background particles. However, thanks to quantum coupling, when the one particle that has been bounced back is received, and "read" by the receiver, then the state of it's matching particle in the local storage also changes, and if you monitor those changes, you effectively discretise your receiver, massively boost the SNR, and mean you can pick the "data" out from the background?

I clearly don't understand it then. I thought you send out a bunch of particles, which are paired to particles you retain. When the "sent particles hit something which alters their spin, the spin in the retained particle changes indicating that the "sent" particle hit something. Not a reflected/returned particle detection.
This is clearly way above my head and I work in defence and did radar detection and analysis in the RN. LOL

As I said it's magic, I did wonder whether to post it in the science thread at first but thought it was interesting enough for people who have an interest in aircraft.
Could the problem be that we are thinking about it with things we understand ie radar, when what it is is a giant leap forward in ability,
say going from sound detection of aircraft to radar, both doing the same job but totally different systems.

[anonymous-user]

AshVX220 said:

I clearly don't understand it then. I thought you send out a bunch of particles, which are paired to particles you retain. When the "sent particles hit something which alters their spin, the spin in the retained particle changes indicating that the "sent" particle hit something. Not a reflected/returned particle detection.
This is clearly way above my head and I work in defence and did radar detection and analysis in the RN. LOL

The problem is that a particles "spin" is not changed by "hitting something" because as far as a particle is concerned, all matter (inc the air) is "something"

A beam of particles is reflected from a target when that target size exceeds the wavelength of the beam (give or take, i'm simplifying here) which is why the higher the frequency of a radar beam, the smaller the object it can detect.

I think that's why i'm (maybe) correct in assuming it's simply an technique to descretise the beam particles from background radiation, and hence (massively) boost the systems SNR!

If the particle was changed by hitting the target object, then this quantum radar wouldn't even need a receiver because you would have range and bearing information without needing to get anything back from the target. That would be good because the repetition rate, and hence area scanning capability of a radar system is directly proportional to it's ranging capability, because between TX pulses you need to wait for the longest return pulse to get back to the receiver (ignoring trick temporal post processing techniques that can / are used to interleave pulses)

Edited by anonymous-user on Thursday 24th October 12:28

[spikep]

AshVX220 said:

This is clearly way above my head and I work in defence and did radar detection and analysis in the RN. LOL

I think it the RN bit!!! If you had studied harder you could have had more letters in the abbreviation as per RAF.

Edited by spikep on Thursday 24th October 16:28

[AshVX220]

spikep said:

AshVX220 said:

This is clearly way above my head and I work in defence and did radar detection and analysis in the RN. LOL

I think it the RN bit!!! If you had studied harder you could have had more letters in the abbreviation as per RAF.

Edited by spikep on Thursday 24th October 16:28

[Krikkit]

AshVX220 said:

I clearly don't understand it then. I thought you send out a bunch of particles, which are paired to particles you retain. When the "sent particles hit something which alters their spin, the spin in the retained particle changes indicating that the "sent" particle hit something. Not a reflected/returned particle detection.
This is clearly way above my head and I work in defence and did radar detection and analysis in the RN. LOL

That's quantum entanglement - create two particles in the same process, then at some stage "measure" it, i.e. push it through a slit experiement or something. The wavefunction of the measured particle collapses, and effects the wave function of the opposite particle which was created at the same time. This can only really be done in very controlled environments i.e. a vacuum under carefully controlled conditions in a lab. In the real world the entanglement is lost.

This uses a newish idea, "quantum illumination" - even though the two signals aren't fully entangled once you've transmitted and received the return signal, they're similar enough that you can distinguish that it was definitely your signal rather than background noise that's come back. Normal RADAR signals can't do this, as you haven't got any firm idea of the quantum state of your outgoing signal.

[JuniorD]

Sounds like the dreams stuff is made from

[IforB]

Well, my head is fried.