Quantum astronomy could make telescopes bigger and better than ever

Light from distant sources must pass through space, Earth’s atmosphere, and telescope optics to be detected. Most photons are lost due to dust, atmospheric absorption, and optical inefficiencies. Larger mirrors and detectors improve photon collection and image clarity, but physical and economic constraints limit telescope size and achievable sharpness. Radio astronomy uses interferometry, where multiple smaller telescopes act as one observatory by precisely timing photon arrivals and combining signals to form interference patterns. Greater separation between telescopes increases spatial resolution, enabling Earth-scale baselines to image regions around the Milky Way’s supermassive black hole. Optical interferometry is older but has been harder to scale because visible-light systems suffer significant photon loss between telescopes. Quantum-driven advances suggest a path to address this limitation and build larger optical interferometers.

"For the light from faraway stars and galaxies to reach and be detected by our telescopes, it first has to beat the odds. Of the photons of light that avoid clouds of dust and other deep-space obstructions to reach our planet, most don't make it through Earth's thick atmosphere, let alone through a telescope's loss-prone optics. Astronomers boost these odds by building telescopes with bigger light-gathering mirrors or detectors, which in turn collect more photons and deliver crisper, clearer images."

"Radio astronomy has long relied upon an esoteric workaround: using a technique called interferometry to make arrays of smaller telescopes collectively act as one giant observatory. Through exquisite timing to track the arrival of photons from each telescope, essentially all the light soaked up by the entire array can be combined to make interference patterns from which images can be extracted. And the greater the baseline separation between an array's individual telescopes, the higher the spatial resolution of the array's resulting images will be."

"this has allowed radio astronomers to, for instance, construct arrays with a baseline as large as Earth itself, gaining sufficient resolution and sensitivity to map the shadowy boundaries of the supermassive black hole at the Milky Way's distant heart. Optical interferometers were invented more than a century ago, but orchestrating and combining signals from multiple telescopes across long baselines has proved much harder to accomplish with visible light compared to the relative ease of working in radio waves."

"One key impediment to making bigger optical interferometers has been the loss of precious photons along the path between them. Now, however, quantum-driven advances are revealing a possible way to solve this problem and create giant optical interferomete"

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