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Even neater is that they are using quantum entanglement in radar to detect stealth planes: https://www.popsci.com/china-quantum-radar-detects-stealth-planes-mis

Even neater is that they are using quantum entanglement in radar to detect stealth planes: https://www.popsci.com/china-quantum-radar-detects-stealth-planes-missiles#page-2 https://www.popsci.com/china-quantum-radar-detects-stealth-p...

misterprime 8y ago
From the article: they are planning to do this, and hopeful that it will work. Not actually using it yet.
- seanmcdirmid 8y ago
  Also, if they got it to work they would surely keep it secret.
  - JackFr 8y ago
    Also, if they didn't get it to work they would surely keep it secret.
    - seanmcdirmid 8y ago
      Yes, and if the military was involved at all, they wouldn’t even talk about the possibility.
barbegal 8y ago
I understand the core concept of quantum radar but does it actually work in practice as a radar? i.e. you can resolve targets with a small range and angular resolution.
- mike00632 8y ago
  Theoretically you would combine the new tech with the old tech. Quantum state would be another measurement to make on the incoming wave on top of measurements like frequency and amplitude.
madeuptempacct 8y ago
Yea, you have to explain this. It made no sense when I first read it, and it still makes no sense. Here is how radar works: You shine a flashlight somewhere. If there is an object within range, some of the light is reflected back at you and you know there is an object. This is literally what radar does. So, what part of this, and how, does this "quantum" magic affect?
- nabla9 8y ago
  It works like normal radar, except that they send one entangled photon towards the plane and keep the other. When the reflection returns, they can use the entanglement to sort out signal from noise much better and radar is safe from jamming and spoofing.
  - madeuptempacct 8y ago
    Thanks, this helps a lot, but just to clarify: Originally "We 'shine' a bunch of photons at an object, and see if they come back. Except there could be dragged decoy spamming photons back at us, and we don't know if there is. Or it could be sending out so much light, our photons coming back are lost in the mix." With quantum: "We can verify that any photons that get reflected are the ones that we sent out and check only our photons when flooded with photons from enemy flashlights." Right?
    - Filligree 8y ago
      Right. Oversimplifying a lot, it's putting a name tag on the photons. Then you can sort out the tagged ones from all the others, drastically reducing the practical noise floor.
      - misterprime 8y ago
        Interesting. Is generating entangled protons so trivial that this is feasible now? It seems like it would take millions (more?) of entangled protons per second to achieve this. And then these can be sensed, verified, and measured at such speed that it could be used as radar? It sounds far fetched, but I would love to know if this process is already that quick and easy.

misterprime 8y ago

From the article: they are planning to do this, and hopeful that it will work. Not actually using it yet.

seanmcdirmid 8y ago
Also, if they got it to work they would surely keep it secret.
- JackFr 8y ago
  Also, if they didn't get it to work they would surely keep it secret.
  - seanmcdirmid 8y ago
    Yes, and if the military was involved at all, they wouldn’t even talk about the possibility.

barbegal 8y ago

I understand the core concept of quantum radar but does it actually work in practice as a radar? i.e. you can resolve targets with a small range and angular resolution.

mike00632 8y ago
Theoretically you would combine the new tech with the old tech. Quantum state would be another measurement to make on the incoming wave on top of measurements like frequency and amplitude.

madeuptempacct 8y ago

Yea, you have to explain this. It made no sense when I first read it, and it still makes no sense. Here is how radar works: You shine a flashlight somewhere. If there is an object within range, some of the light is reflected back at you and you know there is an object. This is literally what radar does. So, what part of this, and how, does this "quantum" magic affect?

nabla9 8y ago
It works like normal radar, except that they send one entangled photon towards the plane and keep the other. When the reflection returns, they can use the entanglement to sort out signal from noise much better and radar is safe from jamming and spoofing.
- madeuptempacct 8y ago
  Thanks, this helps a lot, but just to clarify: Originally "We 'shine' a bunch of photons at an object, and see if they come back. Except there could be dragged decoy spamming photons back at us, and we don't know if there is. Or it could be sending out so much light, our photons coming back are lost in the mix." With quantum: "We can verify that any photons that get reflected are the ones that we sent out and check only our photons when flooded with photons from enemy flashlights." Right?
  - Filligree 8y ago
    Right. Oversimplifying a lot, it's putting a name tag on the photons. Then you can sort out the tagged ones from all the others, drastically reducing the practical noise floor.
    - misterprime 8y ago
      Interesting. Is generating entangled protons so trivial that this is feasible now? It seems like it would take millions (more?) of entangled protons per second to achieve this. And then these can be sensed, verified, and measured at such speed that it could be used as radar? It sounds far fetched, but I would love to know if this process is already that quick and easy.