Quantum mechanics remained a mystery even for the scientists till now. Not every secret was revealed till date and even before this, the defence industry jumped at it and now is planning to create radars using the principles of quantum mechanics. Quantum radars are the new rage and before discussing about whether Quantum radars can or cannot make fifth generation fighters obsolete, let’s discuss about how these radars will work.

Quantum entanglement

Quantum entanglement is a physical phenomenon in which two particles are entangled and supposedly share information at greater speeds than the speed of light. This concept was first proposed by Einstein in a joint paper with Boris Podolsky and Nathan Rosen in 1935 and later on by different scientists and different researches. This concept initially blew the min of Einstein as this concept breaks the fundamental law of the universe that nothing will travel at more than the speed of light and also violates the “Theory of Relativity”.

            This concept basically defines the measurement of physical quantities such as position, momentum, spin and polarization of two entangled particles. Modern researches have proved that measurement of physical properties such as position, momentum, spin and polarization of the entangled particles in some cases were found to be perfectly correlated. Let me explain this by an example.

Consider there are two quantum entangled particles in an orbital. As per the rule, if we try to measure the spin of one particle in one direction, the spin of the other particle should always be in the opposite direction in order to balance the momentum. As soon as the spin of the measured particle is reversed, the other particle in the same orbital changed its spin instantly. This was performed by separating the particles hundreds of miles away and the change was instantaneous. This exact phenomenon baffled the scientists because for the change to occur instantaneously over hundreds of miles, the information should transmit at speeds greater than the speed of light.

 This comes on the basis of Heisenberg’s uncertainty principle that’s at a given point of time, both the position and momentum of particles cannot be determined precisely in an orbital which means that if position is determined precisely based on initial conditions, the momentum cannot be determined precisely and vice versa.

Though we don’t need to go more deeper into quantum mechanics, this basic phenomenon is enough for us to understand the concept of quantum radars as even scientists aren’t clear about why this occurs so lets leave it to them and dive into another basic phenomenon we need to know in order to understand the concept of quantum radars. 

Quantum illumination

Quantum illumination works on the basic principle of Quantum entanglement. This works between a signal and an idler electromagnetic mode. These signals can be sent into space or towards an object and it will either be reflected or will get lost into space depending on the target. 

This concept was first put forth by the scientists at MIT in 2008. In this setup, the sender prepares two sets of entangled systems which are named as signaller and idler. The idler set is retained by the system where as the signal is sent onto the low reflective surface in bright noise environment. This reflection is then combined with the idler system in a joint quantum measurement system resulting in two possible outputs, object is present or it is absent. This process is repeated several times so that many pairs of idler and signal systems are collected.

Idler and Signal System

Advantages of these systems over the traditional detection systems is that in low energy states, where the mean number of photons in each signal system is less that one, the probability of detecting the target is remarkable. An important feature of this system is that the quantum entanglement between the idler and the reflected system is completely lost in the process. But, the remaining quantum correlations between the idler and reflected signals can only be created by the existence of entanglement between idler and signal systems. As the reflected signal is quantum correlated with the idler system, this signal can be distinguished from the clutter of other background photons.

Foundation

The first demonstration of quantum radar was done by an international team in 2015. In this demonstration, they have created a stream of entangled visible-frequency photons and split them into half.one half was the signal beam and other half was the idler beam. These beams were then converted to microwave frequencies and were sent and received by normal radar systems. The reflected beam was then converted back to visible-frequency photons and was then compared with the idler beam.

Because of the existence of quantum correlations between the idler and signal systems, even though there was a lot of background noise and with correct equipment, the entangled photons can be filtered out and the object can be detected.

Advantages and Disadvantages

These types of radar systems cannot be jammed in a literal sense as of now because in order to jam this system one needs to know the initial condition of the photons of the idler and signal system and without that knowledge, it is really tough to jam the signals from this system. Another advantage is that the detection accuracy as discussed above is very high and this can work in environments with a lot of background noise. We can safely assume that these radar systems once deployed will detect fifth-gen fighters as these are not regular microwave systems and the entanglement between the idler and signal system will still remain after being reflected or refracted.

            Disadvantages as of now are the implementation and implications of these systems, the hardware changes to be made to current systems and the reliability of these systems is still a question as only prototypes have been showcased and not working products. Anyways we can safely assume that the future of radar systems looks bright with the advent of quantum mechanics.

Status and countries working on this program ?

United States & Allies: A joint U.S.-British-Canadian-German project in 2015 reportedly tested a quantum radar with a “potential” range of only twenty kilometers. And in the mid-2000s Lockheed took out a patent for a quantum ‘spooky radar,’ though there has been no new information on the program since 2008. This may either reflect a high degree of secrecy vested in the project, or to the contrary, a lack of meaningful progress.

China : In September 2016, China claimed its China Electronic Technology Group Corporation (CETC) had developed a working quantum radar with a range of 100 kilometers (sixty-two miles). This was reportedly achieved through the development of highly efficient single-photon detectors ( this article has a more detailed technical explanation). It’s worth noting that many commentators are skeptical that the Chinese quantum radar is close to being usable under nonlaboratory conditions.

Canada: In April 2018 it was reported that the Canadian Department of National Defense was investing $2.7 million in research at the University of Waterloo to investigate quantum radar technology. This brings Canada into a technological race in which China apparently has taken the lead.

India: DRDO with a various educational institution is working on multiple projects in quantum computing covering the following :

  • Single Photon Generation
  • Single Photon Detection
  • Photonic Interconnects
  • Quantum Key Distribution (QKD)
  • Quantum Communication

The DRDO Young Scientist Lab recently demonstrated QKD and Quantum random number generator. However the current status of Single photon generation and detection is not known.

Bhagawan Hindustani

Indian First, Engineer Next

By Alpha Defense

Alpha Defense initially a solo venture but now a defense group by people from various demographics of India covering defense news and updates. We believe in unbiased analysis of every subject in hand. Our mission is to provide simplfiied defense information to the public.

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