The GHZ paradox exposes a fundamental conflict between quantum mechanics and any local realistic description. An international team encoded a GHZ-type scenario into coherent light and produced photons that occupy a 37-dimensional quantum state space simultaneously, a new high-dimensional demonstration of nonclassical behavior. The experiment, reported in Science Advances, strengthens our understanding of quantum nonlocality and may enable higher-capacity quantum communication and other high-dimensional quantum technologies.
Scientists Create Photons That Simultaneously Occupy 37 Quantum Dimensions
This Experiment Created Light in 37 DimensionsSAKKMESTERKE/SCIENCE PHOTO LIBRARY - Getty Images
An international team of researchers reports a landmark experiment that produced photons occupying 37 quantum dimensions simultaneously, pushing tests of quantum nonlocality to a new, high-dimensional extreme. The work—published in Science Advances and covered by outlets including New Scientist—encodes a Greenberger–Horne–Zeilinger (GHZ)–type paradox into coherent light and demonstrates strikingly nonclassical behavior in a controllable optical platform.
What The Experiment Did
GHZ paradoxes show that quantum predictions cannot be reproduced by any local realistic (proximity-based) model. Rather than testing GHZ scenarios in simple two- or three-state systems, the team expanded the idea into a much larger state space. By carefully encoding and manipulating coherent light across color and wavelength channels, they created photonic states that require 37 orthogonal reference states (a 37-dimensional Hilbert space) to describe — often summarized as "photons occupying 37 dimensions." This phrasing refers to quantum state complexity, not extra spatial dimensions.
The experiment demanded precise control of coherence across many modes and careful measurement to verify GHZ-type contradictions at high dimensionality. According to the authors, these are among the strongest nonclassical effects observed in optical systems to date.
"This experiment shows that quantum physics is more nonclassical than many of us thought," said Zhenghao Liu of the Technical University of Denmark, a co-author. "It could be that 100 years after its discovery, we are still only seeing the tip of the iceberg."
Why It Matters
Extending GHZ tests into high-dimensional systems has two main benefits. Scientifically, it sharpens our understanding of how quantum mechanics departs from classical intuition and highlights regimes where classical descriptions fail dramatically. Practically, high-dimensional photonic states can carry more information per particle and may enable more robust or higher-capacity quantum communications, stronger quantum cryptography protocols, and new avenues for quantum computing and sensing.
The authors argue that the techniques developed in this experiment open new research paths for exploring quantum advantages in high-dimensional systems and for engineering complex quantum states in photonic platforms.
Context and Caution
"37 dimensions" is shorthand for a 37-dimensional quantum state space; it does not imply extra physical spatial dimensions like those in science fiction. Verification of nonclassicality at such scale is technically demanding and will require further experiments to translate these demonstrations into practical technologies. Still, this result marks a notable step in exploring the richness of quantum theory.
For readers interested in the technical details, see the paper in Science Advances and coverage by New Scientist.
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