Papers › Underdamped Diffusion Bridges with Applications to Sampling

Underdamped Diffusion Bridges with Applications to Sampling

2 Mar 2025arXiv:2503.01006archive 2025-07-28

Denis Blessing, Julius Berner, Lorenz Richter, Gerhard Neumann

We provide a general framework for learning diffusion bridges that transport prior to target distributions. It includes existing diffusion models for generative modeling, but also underdamped versions with degenerate diffusion matrices, where the noise only acts in certain dimensions. Extending previous findings, our framework allows to rigorously show that score matching in the underdamped case is indeed equivalent to maximizing a lower bound on the likelihood. Motivated by superior convergence properties and compatibility with sophisticated numerical integration schemes of underdamped stochastic processes, we propose \emph{underdamped diffusion bridges}, where a general density evolution is learned rather than prescribed by a fixed noising process. We apply our method to the challenging task of sampling from unnormalized densities without access to samples from the target distribution. Across a diverse range of sampling problems, our approach demonstrates state-of-the-art performance, notably outperforming alternative methods, while requiring significantly fewer discretization steps and no hyperparameter tuning.

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check_stop_grad DenisBless/UnderdampedDiffusionBridges/algorithms/common/utils.py official repository unverified MIT (permissive) · 29ab22cf1e391158 · report
get_cosine_schedule DenisBless/UnderdampedDiffusionBridges/algorithms/common/scheduler.py official repository unverified MIT (permissive) · 3a7853161909da1d · report
get_learning_rate_scheduler DenisBless/UnderdampedDiffusionBridges/algorithms/common/learning_rate_scheduler.py official repository unverified MIT (permissive) · 896621e81a8c000f · report
get_linear_schedule DenisBless/UnderdampedDiffusionBridges/algorithms/common/scheduler.py official repository unverified MIT (permissive) · d85b357fbdeb22d7 · report
init_langevin DenisBless/UnderdampedDiffusionBridges/algorithms/common/init_diffusion_model.py official repository unverified MIT (permissive) · d443d828e92a9ae7 · report
init_underdamped DenisBless/UnderdampedDiffusionBridges/algorithms/common/init_diffusion_model.py official repository unverified MIT (permissive) · ec4e879e1a90f33d · report
neg_elbo DenisBless/UnderdampedDiffusionBridges/algorithms/overdamped/overdamped_rnd.py official repository unverified MIT (permissive) · 0a3afc9623a6941a · report
per_sample_rnd DenisBless/UnderdampedDiffusionBridges/algorithms/overdamped/overdamped_rnd.py official repository unverified MIT (permissive) · 866334c87a4478ef · report
rnd DenisBless/UnderdampedDiffusionBridges/algorithms/overdamped/overdamped_rnd.py official repository unverified MIT (permissive) · 8cce7df513db5677 · report
sample_kernel DenisBless/UnderdampedDiffusionBridges/algorithms/common/utils.py official repository unverified MIT (permissive) · 80005c2f78f46bf7 · report

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