4 ms·

Quantum radar has been demonstrated for the first time

deleted 7y ago
[deleted]
magicsmoke 7y ago
>The researchers go on to compare their quantum radar with conventional systems operating with similarly low numbers of photons and say it significantly outperforms them, albeit only over relatively short distances. No rendering stealth aircraft obsolete just yet
- krzat 7y ago
  Only over short distances? Is this because entangled photons decohere as they go longer?
  - lisper 7y ago
    Yes, exactly.
- 420codebro 7y ago
  Deployed a networked phased-array and you can point missiles at the vector as it comes into that SAM’s range.
- deleted 7y ago
  [deleted]
xt00 7y ago
Here’s some background on the concept: https://physics.aps.org/articles/v8/18 https://physics.aps.org/articles/v8/18 Basic idea is that you send out a microwave signal and at the same time send entangled microwaves/photons (in the microwave band) into a trap where they basically spin around “idling”/waiting for the potential weak signal to come back. You then feed both the returned signal which is super weak and the idled signal into a josephsen parametric converter. Basically an amplifier based upon a Josephsen junction. The result is that using that type of amplifier it amplifies signals that are quantum entangled more than it amplifies non entangled signals. And you get increased SNR on your signal you get back. So the microwave still has to hit the target and bounce back to you / receiver station you just can use a much weaker signal to transmit the microwave and as a result it acts similarly to passive radar that uses ambient RF to detects objects in the air.
- anfractuosity 7y ago
  I'm confused though, as it says the act of reflection destroys the entanglement? Is entanglement not a binary property though?
  - _Microft 7y ago
    As far as I know such situations can be described by density matrices. https://en.wikipedia.org/wiki/Density_matrix https://en.wikipedia.org/wiki/Density_matrix
- mrfusion 7y ago
  Makes me wonder if this could be applied to cameras? With visible light instead of microwaves.
  - ganzuul 7y ago
    Don't understand it, but one guy interviewed on the subject said resolution is a function of all the entangled photons. That seems to mean you circumvent the diffraction limit.
fspeech 7y ago
First published result? There were reports of military work before: https://www.scmp.com/news/china/diplomacy-defence/article/2151086/chinas-latest-quantum-radar-wont-just-track-stealth https://www.scmp.com/news/china/diplomacy-defence/article/21... This publication gave some credibility to the earlier reports of presumably classified work.
Haga 7y ago
Here's to good health and billions wasted in stealth
ganzuul 7y ago
Some more recent discussion: https://hackaday.com/2019/08/26/quantum-radar-hides-in-plain-sight/ https://hackaday.com/2019/08/26/quantum-radar-hides-in-plain...
bookofjoe 7y ago
https://news.ycombinator.com/item?id=20820196 https://news.ycombinator.com/item?id=20820196

deleted 7y ago

[deleted]

>The researchers go on to compare their quantum radar with conventional systems operating with similarly low numbers of photons and say it significantly outperforms them, albeit only over relatively short distances. No rendering stealth aircraft obsolete just yet

krzat 7y ago
Only over short distances? Is this because entangled photons decohere as they go longer?
- lisper 7y ago
  Yes, exactly.
420codebro 7y ago
Deployed a networked phased-array and you can point missiles at the vector as it comes into that SAM’s range.
deleted 7y ago
[deleted]

xt00 7y ago

Here’s some background on the concept: https://physics.aps.org/articles/v8/18 https://physics.aps.org/articles/v8/18 Basic idea is that you send out a microwave signal and at the same time send entangled microwaves/photons (in the microwave band) into a trap where they basically spin around “idling”/waiting for the potential weak signal to come back. You then feed both the returned signal which is super weak and the idled signal into a josephsen parametric converter. Basically an amplifier based upon a Josephsen junction. The result is that using that type of amplifier it amplifies signals that are quantum entangled more than it amplifies non entangled signals. And you get increased SNR on your signal you get back. So the microwave still has to hit the target and bounce back to you / receiver station you just can use a much weaker signal to transmit the microwave and as a result it acts similarly to passive radar that uses ambient RF to detects objects in the air.

anfractuosity 7y ago
I'm confused though, as it says the act of reflection destroys the entanglement? Is entanglement not a binary property though?
- _Microft 7y ago
  As far as I know such situations can be described by density matrices. https://en.wikipedia.org/wiki/Density_matrix https://en.wikipedia.org/wiki/Density_matrix
mrfusion 7y ago
Makes me wonder if this could be applied to cameras? With visible light instead of microwaves.
- ganzuul 7y ago
  Don't understand it, but one guy interviewed on the subject said resolution is a function of all the entangled photons. That seems to mean you circumvent the diffraction limit.

fspeech 7y ago

First published result? There were reports of military work before: https://www.scmp.com/news/china/diplomacy-defence/article/2151086/chinas-latest-quantum-radar-wont-just-track-stealth https://www.scmp.com/news/china/diplomacy-defence/article/21... This publication gave some credibility to the earlier reports of presumably classified work.

Haga 7y ago

Here's to good health and billions wasted in stealth

ganzuul 7y ago

Some more recent discussion: https://hackaday.com/2019/08/26/quantum-radar-hides-in-plain-sight/ https://hackaday.com/2019/08/26/quantum-radar-hides-in-plain...

bookofjoe 7y ago

https://news.ycombinator.com/item?id=20820196 https://news.ycombinator.com/item?id=20820196