A famous quantum effect used to prove the power of light-based computers might just be a statistical error.
April 20, 2026
Original Paper
Boson correlations are spurious for classical states
arXiv · 2604.16283
The Takeaway
Boson sampling is a technique used to demonstrate that quantum computers can outperform classical ones by tracking how photons interfere. This paper argues that the correlations measured in these experiments are actually spurious results of a statistical phenomenon called the Simpson paradox. The authors show that these patterns can emerge from classical physics and symmetry breaking rather than true quantum behavior. This finding challenges the validity of several high-profile claims of quantum advantage in recent years. It suggests that many things we label as quantum might just be math tricks we haven't accounted for yet. This will force the entire field to raise the bar for proving a quantum computer is actually faster.
From the abstract
We show that boson correlations from quantum states with a Glauber-Sudarshan representation of their density matrix which provides a well-behaved probability distribution -- including coherent states, thermal states, and all states that can be deemed classical -- are a manifestation of the Simpson paradox: they are spurious correlations from statistical (ensemble) averages over uncorrelated measurements made in varying geometries, due to a process of symmetry-breaking as a confounding factor. Bo