Reproducing and Extending Brownian Motion in Optical Trap: A Computational Reimplementation of Volpe and Volpe (2013)

Abstract

We present a re-representation and independent simulation of the model introduced by Giorgio Volpe and Giovanni Volpe in their 2013 study of a Brownian particle in an optical trap (Volpe and Volpe, 2013). Rather than duplicating their original plots, we reconstructed the simulations from first principles using Python, implementing stochastic differential equations via finite difference schemes. This work reproduces and validates the key physical regimes described in the original article, including the transition from ballistic to diffusive motion, optical confinement, and velocity autocorrelations. To simulate rotational forces (Grier, 2003) and Kramers transitions (Haenggi et al., 1990), we also extend the analysis to include force perturbations, rotational fields, Kramers transitions, and stochastic resonance. The simulations provide pedagogical insight into stochastic dynamics and numerical modeling, reinforcing the original study's value as a teaching and research tool in statistical and computational physics.

17 pages, 3 figures, 3 python codes