from the we've-come-a-long-ways-from-the-days-of-the-daguerreotype dept.
Quantum radar has been demonstrated for the first time
One of the advantages of the quantum revolution is the ability to sense the world in a new way. The general idea is to use the special properties of quantum mechanics to make measurements or produce images that are otherwise impossible.
Much of this work is done with photons. But as far as the electromagnetic spectrum is concerned, the quantum revolution has been a little one-sided. Almost all the advances in quantum computing, cryptography, teleportation, and so on have involved visible or near-visible light.
Today that changes thanks to the work of Shabir Barzanjeh at the Institute of Science and Technology Austria and a few colleagues. This team has used entangled microwaves to create the world's first quantum radar. Their device, which can detect objects at a distance using only a few photons, raises the prospect of stealthy radar systems that emit little detectable electromagnetic radiation.
The device is simple in essence. The researchers create pairs of entangled microwave photons using a superconducting device called a Josephson parametric converter. They beam the first photon, called the signal photon, toward the object of interest and listen for the reflection.
In the meantime, they store the second photon, called the idler photon. When the reflection arrives, it interferes with this idler photon, creating a signature that reveals how far the signal photon has traveled. Voila—quantum radar!
This technique has some important advantages over conventional radar. Ordinary radar works in a similar way but fails at low power levels that involve small numbers of microwave photons. That's because hot objects in the environment emit microwaves of their own.
In a room temperature environment, this amounts to a background of around 1,000 microwave photons at any instant, and these overwhelm the returning echo. This is why radar systems use powerful transmitters.
Entangled photons overcome this problem. The signal and idler photons are so similar that it is easy to filter out the effects of other photons. So it becomes straightforward to detect the signal photon when it returns.
Ref: arxiv.org/abs/1908.03058 Experimental Microwave Quantum Illumination
(Score: 2) by corey on Saturday August 31 2019, @11:02AM (2 children)
You should classify that tech, then get it into your own indigenous 6th gen fast jet. Then apply heaps of export restrictions.
(Score: 0) by Anonymous Coward on Saturday August 31 2019, @11:31AM (1 child)
it's probably cheaper for the world overall to just open-source it and make "stealth" obsolete: if you want to fly over, ask for permission via a flight plan?
(Score: 0) by Anonymous Coward on Saturday August 31 2019, @11:44AM
The flight plan I filed with the agency lists me, my men, Dr. Pavel here. But only one of you.
(Score: 1, Insightful) by Anonymous Coward on Saturday August 31 2019, @03:01PM (1 child)
Since quantum entanglement effects happen instantly does this mean that the response time is now cut in half? Does it mean that the response only happens in the time it takes the photon to reach its target instead of the time it takes to reach its target and return?
Also I thought that sending useful information via quantum entanglement was impossible. This seems to defy that. Can some similar setup be used for FTL communication? If we receive a photon from a source can we then figure out how to modify it so that the source can get our return signal in a time less than the time it takes for the photon to travel all the way back to the source effectively cutting the communication latency in half?
(Score: 3, Insightful) by Rupert Pupnick on Saturday August 31 2019, @08:04PM
The way I read TFS, you have to wait the same amount of time as you would for a plain old regular radar return signal since the “signal photon” has to make the same round trip at the same speed. Near the end of TFS they allude to the real advantage which is performance in the presence of noise. Since the signal photon is entangled with the idle photon, you can think of it as effectively being tagged. In this way, only energy that originally comes from transmitter is detected. Other noise or interfering sources are ignored. Another way of saying this is that the receiver no longer has to consider the problem of overcoming poor signal to noise ratio.
As a certified Quantum Skeptic (in matters of applications only), I have confess that this is the first practical application I’ve come across that makes understandable (to me) use of quantum principles. Whether anyone can actually build a quantum RF transceiver system that actually works is another question entirely.
(Score: 0) by Anonymous Coward on Saturday August 31 2019, @03:10PM (2 children)
What use is this if the enemy isn't trying to sneak up on you with quantum aircraft?
(Score: 0) by Anonymous Coward on Sunday September 01 2019, @12:59PM (1 child)
Well, maybe we can finally answer the Schrödinger's cat question w/o opening or looking in the box?
My money is on the outcome that the cat has died of old age by now, even if the cat got radioactive...or not. ;-)
rts008
(Score: 2) by pvanhoof on Sunday September 01 2019, @04:49PM
If you didn't feed the cat back then and give it milk or water regularly, the cat has died of starvation. Not old age.
(Score: 2) by takyon on Saturday August 31 2019, @08:47PM
We could use another sensor in there.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 3, Insightful) by JoeMerchant on Saturday August 31 2019, @09:13PM
Single photon? How far can you fling a single photon and expect to receive a reflection of it?
🌻🌻 [google.com]
(Score: 2) by PinkyGigglebrain on Saturday August 31 2019, @10:26PM (1 child)
I didn't read the article but it sounds like this kind of RADAR would allow for both lower power transmitters, since the return signal would couldn't be swamped by ambient noise. Allowing for greater detection range and less likely hood the target would detect the base unit.
And if I'm understanding the interaction between the entangled photons correctly it would mean this tech could not be actively jammed, which normally uses random/loud/fake noise to confuse/overwhelm the receivers. Though passive counter measures like chafe would still work.
Anyone want to bet that they have been using this kind of tech at Area 51 for the last 10 years or so?
"Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
(Score: 2) by takyon on Sunday September 01 2019, @04:38AM
Yes, the response around here is lackluster but this looks like it could be a Big Deal™.
If we believe the Snowden releases, the NSA was/is interested in quantum computing, but not anywhere nearer to making it practical than anyone else. Even though popular legend puts them 10-15 years ahead of the rest of the world on matters of cryptography, signals intelligence, vulnerabilities, etc.
There's so little practical or off-the-shelf quantum computing equipment, maybe the military doesn't have much. Or maybe the quantum radar was working in DARPA 10 years ago. We'll need leaks or FOIA to find out.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 1) by anubi on Sunday September 01 2019, @06:02AM
Once people say they can do this, it's classified, and no one can prove someone's lying, then that someone has yet more FUD to control you with.
This is like playing poker. Who is bluffing? I never was any good at it.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]