Stochastic
resetting is prevalent in natural and man-made systems,
giving rise to a long series of nonequilibrium phenomena. Diffusion
with stochastic resetting serves as a paradigmatic model to study
these phenomena, but the lack of a well-controlled platform by which
this process can be studied experimentally has been a major impediment
to research in the field. Here, we report the experimental realization
of colloidal particle diffusion and resetting via holographic optical
tweezers. We provide the first experimental corroboration of central
theoretical results and go on to measure the energetic cost of resetting
in steady-state and first-passage scenarios. In both cases, we show
that this cost cannot be made arbitrarily small because of fundamental
constraints on realistic resetting protocols. The methods developed
herein open the door to future experimental study of resetting phenomena
beyond diffusion.