September 28, 2026

report by Paul Arnold, Phys.org Author edited by Lisa Lock, reviewed by Robert Egan Scientific Editor Senior Editor This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: fact-checked preprint trusted source proofread There's big news from the quantum world. A quantum computer has been used in space for the first time. The device was aboard a spacecraft in low Earth orbit and demonstrated technology that could eventually help solve a problem that has been bugging satellites for years. The issue is that when orbiting satellites send their raw data back down to Earth, bottlenecks and bandwidth limits slow everything down. One way to overcome this would be to process the raw data in situ before sending it. So a team of physicists led by Philip Walther at the University of Vienna came up with a way that could eventually do just that. Their solution was to build a quantum photonic processor that uses individual light particles, or photons, to perform complex operations using compact optical hardware. But taking the idea from the drawing board to orbit was not without its challenges. Quantum photonic systems are delicate, and radiation, large temperature changes and the vacuum of space could damage their components or disrupt their operation. Of course, it first had to get there. The quantum photonic processor, which consisted of a photon-pair source, a six-mode integrated glass circuit chip, single-photon detectors and control electronics, was loaded aboard a SpaceX Falcon 9 rocket. It was launched into low Earth orbit on June 23, 2025. Once it arrived in orbit, the real work began. To process information, the system shines a laser through a crystal to create pairs of photons. It then sends those light particles through a tiny glass circuit, controlling how they travel and interfere using microscopic heaters. Finally, sensitive detectors catch the light at the other end to measure where the photons emerge. There was a hitch: Half the photon detectors were no longer working after launch, leaving the team with just three of the original six. Despite that setback, the mission achieved its core goals. Over the first eight months in orbit, the system successfully generated, manipulated and detected pairs of photons, performing several different programmed operations. The team also changed the chip settings and carefully tuned the photons to look for a phenomenon called two-photon interference. They successfully observed quantum interference between the light particles even in the harsh conditions of space. But the results are only a first step. There is still plenty of work to do before satellites can run quantum-assisted data processing tasks directly in orbit. As the study authors explain in their paper, which is posted to the arXiv preprint server, "The next step is to close the loop between sensor and processor, encoding Earth-observation data directly into the unitary programmed on the circuit." Reaching that goal will also require ensuring instruments can handle the extreme stresses they will face. "What remains is to keep it stable over the long acquisition times that an inference task demands, as the gradual degradation of the components reduces the coincidence rate." Written for you by our author Paul Arnold, edited by Lisa Lock, and fact-checked and reviewed by Robert Egan-this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you. Simon Steiner et al, In-orbit operation of a programmable quantum photonic processor, arXiv (2026). DOI: 10.48550/arxiv.2609.25248 Journal information: arXiv BSc Biology from University of London. BBC documentary producer with world travel experience. Freelances from southern Spain.

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