  We study the motion of active patchy colloids in an optical trap using
experiments, theory and numerical simulations. To achieve isotropic and
harmonic confinement, we prototype microparticles with a nearly uniform
refractive index and verify that, in the absence of activity, the confined
motion is identical to that of optically homogeneous Brownian particles. If the
activity is turned on by means of vertical AC fields, the density distributions
are described by Boltzmann-like statistics (Gaussian with effective
temperature) only for strongly confining traps, whereas weaker potentials give
rise to non-Gaussian distributions with a bimodal shape. Our results showcase a
simple way to study active soft matter in optical potential landscapes
eliminating the optical torque.
