I have read about proposals to invent quantum telescopes. In my limited understanding, a quantum telescope would be able to defeat the diffraction limit by "cloning" incoming photons, making a number of identical photons, whose average signal can be calculated. I googled "quantum telescopes" and went to the first link, which is a webpage on physicsworld.com. That site said:

 

"Quantum mechanics, rather than a huge telescope, could be the best route to high-resolution space images, according to new research carried out in the UK. If confirmed, a telescope of any size could resolve ever-smaller features of the night sky, allowing astronomers to discover exoplanets and other distant objects much more easily than is currently possible."

 

It also said, "Unfortunately, the technology required to build a telescope using quantum cloning is very far off."

 

I also read, in the August, 2019 issue of Air&Space Smithsonian magazine, about research to enable the imaging of exoplanets by other technology. At least one microwave kinetic induction detector (MKID) is already in use; it is "...more than a camera; it's a photon counter, capable of providing the arrival time, location and energy of every single photon that hits the detector." MKIDs have to be supercooled. But there are also "...already certain kinds of CCDs that can count photons and that some CCDs, when used in combination with multiple filters, can measure the energy of photons."

 

My question is, what is the necessity to develop a quantum telescope when other, already emerging technology is moving toward the imaging of exoplanets?