Fig. 7: Overview of localization scenarios for active particles in motility traps.

As a measure of the efficiency of motility trapping, we numerically calculated the square of the scaled confinement length \(\left\langle {x^2} \right\rangle l_v^{ - 2}\) encoded in color (values are shown inside each plot) as a function of \(\Delta v\tau _{\mathrm{B}}l_v^{ - 1}\) and \(Ll_v^{ - 1}\). Here, L is the box size and the trap depth Δv = V^max − V^min, where V^max and V^min correspond to the respective maximal and minimal velocity. τ_B is the typical Brownian time. In all panels, the trap length is set to l_v = 46.15 σ, with σ the active particle (AP) diameter and V^min = 0. Numerical simulations for a cooling and a heating map are shown in a, c, e and b, d, f, respectively. a, b Data in the absence of an active torque, that is, c = 0 (AP delocalization). c–f Data from numerical simulations in the presence of an active torque where c = +0.6 τ_B (c, e) and c = −1.2 τ_B (d, f) (AP localization). The green filled circles correspond to the experimental conditions presented in this work.