Quantum radar and its implications

In summary: This is a really interesting analogy, and it makes sense. So, if we want to compare the numbers in the box, we can do so without knowing what was originally in the box. But, if we want to know what was originally in the box, we need to know the state of the die before we opened it.
  • #1
GTOM
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https://www.popularmechanics.com/military/a28818232/quantum-radar/
https://www.asiatimes.com/2019/09/article/stealth-killer-quantum-radar-actually-works/?_=3274804
I don't know, whether the above sources are reliable, or not, that is why i ask.

"Quantum radars involve pairing photon particles together, shooting one downrange while keeping the second captive for observation. The downrange particle will act in a certain manner as it bounces off certain objects, behavior that can be observed in the captive particle. The result is much more detailed information about the target than seen in previous radars. "

This is from the first article. What makes it really fantastic for me, that as far as i know, we can't use quantum entanglement for FTL signalling, since the effect is unobservable directly, we can be only sure what happened, when we compare results of the endpoints of entanglement.
But the above part implicates for me, that actually there is a way to observe something has happened to the entangled pair, with only a measurement of the emitter.

https://www.sciencealert.com/scient...d-direct-counterfactual-quantum-communication
That third link also about that possibility, if i understand correctly.

Of course i can totally misunderstand theese parts, but in this case, what makes that quantum radar and imaging any superior to existing methods?
 
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  • #2
GTOM said:
But the above part implicates for me, that actually there is a way to observe something has happened to the entangled pair, with only a measurement of the emitter.

The photon sent downrange has to (conditional on an object being present) bounce back and get combined with its partner in order for the process to work. There's no FTL signalling going on.
 
  • #3
Strilanc said:
The photon sent downrange has to (conditional on an object being present) bounce back and get combined with its partner in order for the process to work. There's no FTL signalling going on.

I also thought about that, but then how it gives any more information than simply measure the phase of the reflected photon? What is the point of entanglement?
 
  • #4
I try to write down my thoughts without saying that its high time to rewrite physics books, or saying that i am the expert of the field, instead of simply a curious one.

I have the analogy of black boxes with dice in it.

So classic example of entanglement is like, we have two boxes with entangled dice. We turn one box upside down, open the boxes, and voila we see the same numbers. The problem is, we break entanglement when we open the boxes, so we can't use this for signalling, we can't tell, whether the other one turned the box or not.

Now, we have a box, send out entangled pairs to an object. We receive some dice, either the ones we sent out and reflected, or from a random noise.
So we compare the ones in the box, and what we received. If we don't know anything about what should be in the box, how does it helps us? How it help us to compare two random set of numbers showed by the dice?
Does the numbers of the box have any clear pattern? In this case can't we make a difference between a clear pattern (like most numbers are 1, or even) and a random set of numbers if the other party shaked the other box with the entangled pairs?
 

1. What is quantum radar?

Quantum radar is a new type of radar system that uses quantum entanglement to detect and track objects. It works by sending out pairs of entangled photons, which are then reflected back by objects in the environment. By measuring the correlation between the two photons, the radar can accurately determine the location and velocity of the object.

2. How is quantum radar different from traditional radar?

Traditional radar systems use radio waves to detect objects, while quantum radar uses entangled photons. This allows quantum radar to have much higher resolution and sensitivity, making it useful for detecting small and stealthy objects that traditional radar may miss. Additionally, quantum radar is not affected by jamming or spoofing, making it more secure.

3. What are the potential applications of quantum radar?

Quantum radar has potential applications in military and defense, as it can detect stealth aircraft and missiles. It can also be used for air traffic control, weather monitoring, and mapping of the Earth's surface. In the future, it may also have applications in quantum communication and quantum computing.

4. Are there any ethical concerns with the use of quantum radar?

There are some ethical concerns surrounding the use of quantum radar, particularly in military and surveillance applications. As with any new technology, there is a risk of it being used for unethical or invasive purposes. It is important for regulations and ethical guidelines to be in place to ensure responsible use of this technology.

5. What are the challenges in implementing quantum radar technology?

One of the main challenges in implementing quantum radar is the need for advanced quantum technology, such as entangled photon sources and detectors. These components are still in the early stages of development and can be expensive. Additionally, there are technical challenges in maintaining the quantum entanglement over long distances and in varying environmental conditions.

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