Quantum telescope could make giant mirrors obsolete

[jakeXT]

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.

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Uncertain times

The reason the GTC and other telescopes need to be so big is to push the maximum resolution. When a photon enters an aperture of a telescope, the uncertainty in its position is reduced to the radius of that aperture. Moreover, according to Heisenberg's uncertainty principle, there is a corresponding uncertainty in its momentum, which defines the photon's initial direction. As the uncertainty in position rises with the widening of the aperture, the uncertainty in its momentum falls – allowing its direction to be determined with greater precision. In other words, telescopes with larger apertures have a smaller "diffraction limit".

Aglaé Kellerer at Durham University began thinking about how quantum mechanics could provide an alternative to overcome the diffraction limit when she came across similar methods used in microscopy and lithography. "The one horizon for the astronomer today is to build larger telescopes. Somehow, at some point, we need to come up with a different approach," she says.
Cloning techniques

The diffraction limit for a telescope aperture is set per photon – but if there were many identical, cloned photons arriving at the same time, the diffraction limit would be reduced by a factor equal to the square root of their number. To achieve this, Kellerer proposes that a quantum "non-demolition" measurement is performed upon each photon passing through the pupil of the telescope. Such a measurement does not reveal specific information about the photon, but only records its passing. After the measurement, the photon is cloned by letting it "de-excite" atoms, which spontaneously emit several identical photons that are then recorded by a detector, which calculates their average signal.

http://physicsworld.com/cws/article/news/2014/apr/29/quantum-telescope-could-make-giant-mirrors-obsolete

[SheilaT]

1. Interesting. I'll have to ask my son the budding astrophysicist about this.

I can tell you that these days they make giant telescopes by arranging multiple mirrors so as to effective create a huge telescope.

And the mirrors really aren't mirrors but highly polished honeycombs of glass.

They build these things at the University of Arizona. If you're near there or make a visit, see if you can get on a tour of the mirror lab. It's beyond cool.

[mindwalker_i]

2. So there's this thing known as the no-cloning theorem

It was developed because a physicist had an idea for using quantum entanglement to send information, which relied on being able to clone an incoming photon so two measurements could be made on it. If cloning were possible, then a sender could prepare photons in such a way that the receiver, after cloning the photons, could determine how the sender prepared them. This would result in FTL communication, and retrocausality comes naturally as a result. It caused the no-cloning theorem to be developed. So I'm wondering whether this only clones part of the photon's state, or whether it will fall victim to the no-cloning theorem too.

[DavidDvorkin]

3. Very cool.