Spectroscopic characterization of rare events in colloidal particle stochastic thermodynamics

Given the remarkable developments in synthetic control over colloidal particle chemical and physical properties, it is interesting to see how stochastic thermodynamics studies may be performed with new, surrogate, or hybrid model systems. In the present work, we apply stochastic dynamics and nonlinear optical light-matter interaction simulations to study non-equilibrium trajectories of individual Yb(III):Er(III) co-doped colloidal and nanoparticles driven by two-dimensional dynamic optical traps. We characterize the role of fluctuations at the single particle level by analyzing position trajectories as well as time-dependent upconversion and downconversion emission intensities. By integrating these two complementary perspectives, we show how the methods developed here can be used to characterize rare events.