Control of non-equilibrium Casimir force

Applied Physics Letters, Volume 118, Issue 14, April 2021. We introduce the concepts of the control theory into the study of non-equilibrium Casimir forces and radiative heat transfer. As an illustration, we consider the plate-plate system for non-equilibrium Casimir forces, where two dielectric plates having different temperatures are separated by a vacuum gap. Previous works have indicated that this system only supports an unstable mechanical equilibrium. Here, we prove analytically and confirm numerically that the equilibrium can be made stable through a feedback control process involving temperature measurement and modulation. Our results show that it should be fruitful to explore the concepts from control theory in the study of the Casimir force and radiative heat transfer.