Exactly solvable diffusions from space-time transformations

We consider a general one-dimensional overdamped diffusion model described by the Itô stochastic differential equation (SDE) ${\mathrm dX_t = \mu(X_t,t)\mathrm dt+\sigma (X_t,t)\mathrm dW_t}$ , where W _t is the standard Wiener process. We obtain a specific condition that µ and σ must fulfil in orde...

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Bibliographic Details
Main Authors: Costantino Di Bello, Édgar Roldán, Ralf Metzler
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:New Journal of Physics
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Online Access:https://doi.org/10.1088/1367-2630/adecbb
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Summary:We consider a general one-dimensional overdamped diffusion model described by the Itô stochastic differential equation (SDE) ${\mathrm dX_t = \mu(X_t,t)\mathrm dt+\sigma (X_t,t)\mathrm dW_t}$ , where W _t is the standard Wiener process. We obtain a specific condition that µ and σ must fulfil in order to be able to solve the SDE via mapping the generic process, using a suitable space-time transformation, onto the simpler Wiener process. By taking advantage of this transformation, we obtain the propagator in the case of open, reflecting, and absorbing time-dependent boundary conditions for a large class of diffusion processes. In particular, this allows us to derive the first-passage time statistics of such a large class of models, some of which were so far unknown. While our results are valid for a wide range of non-autonomous, non-linear and non-homogeneous processes, we illustrate applications in stochastic thermodynamics by focusing on the propagator and the first-passage-time statistics of isoentropic processes that were previously realised in the laboratory by Brownian particles trapped with optical tweezers.
ISSN:1367-2630