The latest NS has an article about quantum telescopes:

Planet-sized telescopes could be possible using quantum technique.

which has me confused, because I just read an article from last week’s issue about “planet sized telescopes”, and orbital telescopes with even larger effective size, that doesn’t mention quantum stuff.

So what’s confusing me is:

- Is quantum computing really needed to get these things to work?
- How do they work anyway? Even for a land-based version I don’t see how they measure the inclination sufficiently accurately to make two or more telescope(s) effectively a single instrument. Even more so for orbital telescopes.

(Confusion partially resolved, the on-line article was from 2 years ago, not this week.)

The on-line article may be subscriber only, so here it is:

Huge networks of interconnected telescopes may run into image-sharpening problems that classical physics can’t handle. Accounting for the quantum properties of starlight could allow astronomers to get past these constraints

By Karmela Padavic-Callaghan

2 May 2022

Quantum computers that can catch their own mistakes could make it possible to build huge telescopes the size of a planet. The approach would allow astronomers to get past constraints with current telescopes to clearly view distant objects in space.

Astronomers trying to take images of faraway stars and planets are at the mercy of whatever faint light reaches their telescopes. They can increase the resolution by using arrays of interconnected telescopes called astronomical interferometers. However, to obtain sharp images of some of the most distant objects, such arrays would have to span thousands of kilometres and, at this size, image-sharpening techniques based on classical physics no longer work.

Astronomers can often ignore light’s quantumness, but when so little of it reaches the telescope its particles no longer behave in classical ways, says Daniel Gottesman at the University of Maryland, who wasn’t involved with the project. “That means this light is really quantum, there’s just no way around that,” he says.

Zixin Huang at Macquarie University in Australia and her colleagues have now found that quantum methods could enable large interferometers to handle light that effectively arrives one photon at a time and resolve fuzzy images. The approach borrows a technique originally developed for communication between quantum computers.

As particles of starlight enter the telescopes, they would be recorded into a quantum version of a hard drive made up of specially prepared atoms. Their energies and arrival times would result in the hard drive atoms changing into a different state.

Light from the same star reaching the interferometer would be quantum-mechanically entangled. This means that the individual telescopes can effectively act as one large telescope without losing any data when they talk to each other to create an image.

To process that information, scientists would use quantum computers programmed to find and correct their own mistakes during computation. Without this, the process would be vulnerable to glitches and errors that would affect the final image.

Huang’s team is the first to propose using these self-correcting quantum computers for astronomy and the analysis shows that they could produce sharp images even if more than 10 per cent of the starlight data succumbed to glitches.

Thanks to quantum mechanics, a giant telescope using the team’s method could have a resolution thousands of times higher than any existing or planned interferometer.

This is an example of using quantum technology for a task where a classical counterpart simply doesn’t exist and it gives a way of getting around a classical limitation, says Emil Khabiboulline at Harvard University.

Many of the components needed to build a telescope with the new system have already been individually tested, but some obstacles remain, like making sure that it isn’t too costly for distant telescopes in an array to exchange quantum information. “There are many more challenges that need to be addressed for a planet-sized device, but this is a good first step,” says Huang.

A similar approach could be used to help see further into space and uncover previously inaccessible details. Huang is already studying how to improve our understanding of signals that come from water or hydrogen on planets outside of the solar system, which could be indicators of life.

Reference: arXiv, arxiv.org/abs/2204.06044