Researchers at the Technical University of Denmark (DTU) and international partners have demonstrated a quantum advantage for a learning task on a photonic system. A new paper in Science reports that entangled light can significantly reduce the number of measurements needed to learn the behavior of a complex, noisy quantum system. This is positioned as the first proven quantum advantage for a photonic system, and the work was carried out in collaboration with colleagues from the U.S., Canada, and South Korea.
The experiment used entangled light to learn the behavior of a system where light pulses shared the same noise pattern. Two beams of light were prepared and entangled, with one beam used to probe the system and the other as a reference. A joint measurement of the two beams was then performed, which is said to cancel much of the measurement noise and provide more information per trial than a classical approach. Ulrik Lund Andersen, a professor at DTU Physics, noted that they were able to learn the behavior of their system in 15 minutes, while a comparable classical approach would take around 20 million years.
The experiment was set up in the basement at DTU Physics and used well-known optical components. The researchers note that the gain comes from the measurement technique, not a perfect measuring device. The findings suggest that entangled light could be a useful tool for sensing and machine learning. The partners behind the paper are researchers from the University of Chicago, Perimeter Institute, University of Waterloo, Caltech, MIT, and KAIST.
Read the full announcement from DTU here and the paper in Science here.
September 27, 2025
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