Anisotropic particles near surfaces: Self-propulsion and friction

Abstract

We theoretically study the phenomenon of self-propulsion through Casimir forces in thermal non-equilibrium. Using fluctuational electrodynamics, we derive a formula for the self-propulsion force for an arbitrary small object in two scenarios, i) for the object being isolated, and ii) for the object being close to a planar surface. In the latter case, the self-propulsion force (i.e., the force parallel to the surface) increases with decreasing distance, i.e., it couples to the near-field. We numerically calculate the lateral force acting on a hot spheroid near a surface and show that it can be as large as the gravitational force, thus being potentially measurable in fly-by experiments. We close by linking our results to well-known relations of linear response theory in fluctuational electrodynamics: Looking at the friction of the anisotropic object for constant velocity, we identify a correction term that is additional to the typically used approach.

13 pages, 8 figures (v2: References updated)

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• Microscopic theory of photon-induced energy, momentum, and angular momentum transport in the nonequilibrium regime
• Moving Media as Photonic Heat Engine and Pump
• Inhomogeneity-Induced Casimir Transport of Nanoparticles
• Quantum propulsion and trapping of nano-objects by inhomogeneity-induced lateral Casimir forces
• Quantum Self-Propulsion of an Inhomogeneous Object out of Thermal Equilibrium
• Spontaneous Torque on an Inhomogeneous Chiral Body out of Thermal Equilibrium
• Propulsion force and heat transfer for nonreciprocal nanoparticles