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Title: Photon-loss threshold for classical simulability of Gaussian boson sampling
Plain: Gaussian boson sampling sends squeezed light through a large optical network and records where photons arrive; it was used to claim quantum advantage. Losing photons makes the task easier for classical computers, and the loss level at which it becomes easy is not known exactly.
Precise: For Gaussian boson sampling with $M$ modes, $K$ single-mode squeezed inputs of squeezing r, a Haar-random interferometer and uniform transmission $\eta$, find the boundary $\eta_c(r, K, M)$ separating classically efficient sampling to fixed total-variation error from sampling hard under standard conjectures, as M, K go to $\infty$ at fixed ratio.
Settled by: A classical algorithm efficient below $\eta_c$ together with a hardness proof above it, for the same scaling family.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: partially-resolved
Status note: Oh et al. (arXiv:2306.03709, Nature Physics 2024) simulated reported experiments by exploiting their loss; sufficient conditions for hardness of lossy GBS appeared in 2025 (arXiv:2511.07853).
Posed since: (empty)