Researchers in the US have demonstrated how quantum entanglement could be used to detect optical signals from astronomical sources at the single-photon level. Published in Nature, a team led by Pieter-Jan Stas at Harvard University showed how extremely weak light signals could be detected across a fiber link spanning more than 1.5 km—possibly paving the way for optical telescopes with unprecedented resolution.

Interferometry is often used in astronomy to produce high-resolution images of distant objects. By combining light collected across networks of spatially separated detectors, the technique can achieve resolutions comparable to those of a single telescope with a diameter equivalent to the distance between them. In continent-spanning networks like the Event Horizon Telescope, it was used to create the first direct image of a black hole (Messier 87) in 2019.