Dynamical computation of the density of states using nonequilibrium importance sampling.

Sampling with a dynamics that breaks detailed balance poses a challenge because the resulting probability distribution is not typically known. In some cases, most notably in uses of the Jarzynski estimator in statistical physics, astrophysics, and machine learning, it is possible to estimate an equilibrium average using nonequilibrium dynamics. Here, we derive a generic importance sampling technique that leverages the statistical power of configurations that have been transported by nonequilibrium trajectories. Our approach can be viewed as a continuous generalization of the Jarzynski equality that can be used to compute averages with respect to arbitrary target distributions. We establish a direct relation between a dynamical quantity, the dissipation, and the volume of phase space, from which we can compute the density of states. We illustrate the properties of estimators relying on this sampling technique in the context of density of state calculations, showing that it scales favorable with dimensionality. We also demonstrate the robustness and efficiency of the approach with an application to a Bayesian model comparison problem of the type encountered in astrophysics and machine learning.