cs.LGOct 9, 2026

SBNO : Schrödinger Bridge Neural Operator for the Forward and Inverse Problems under Missing Information

Authors: Jaehyeon Park, Inhyeok Jeong, Noseong Park

Organizations: SolverX · KAIST

Abstract

Partial differential equation (PDE) surrogate modeling often relies on either dense observations or access to governing equations/physics constraints. In practice, observations can be sparse and partial, and the underlying physics may be partially specified or unavailable. We introduce SBNO, an equation-free paired-data diffusion bridge matching framework that learns conditional operators for both forward and inverse PDE problems under partial observations. SBNO uses diffusion Schrödinger bridge matching to learn a pair of time-dependent drifts from a mask-aware endpoint coupling that preserves empirical input-solution pairing during training and supports both PDE-task directions within a single framework. At inference time, SBNO produces a deterministic point reconstruction by integrating the probability-flow ODE constructed from the learned drift pair, without inference-time observation or PDE guidance-weight tuning. On five PDE benchmarks with 5% observations, SBNO achieves superior or comparable accuracy to baselines while demonstrating lower test-instance error dispersion. Furthermore, SBNO is at least 9.7×9.7 \times faster and reduces GPU memory by at least 4.3×4.3 \times compared to guided-diffusion baselines.

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