Casimir interactions of complex surfaces and materials

Understanding the vacuum state of a system is a challenge of fundamental physics and associated important technologies. If confined within boundaries, quantum vacuum fluctuations manifest themselves by the generation of Casimir forces. However, boundaries between interacting bodies possess in many cases nanoscale surface roughness, which is both difficult to avoid and control. When two bodies are separated by a small distance (less than 100 nm) then nanoscale roughness starts to play an important role on the Casimir interaction between the bodies and their adhesion upon contact. Control of this short-distance interaction is crucial for micro and nanoelectromechanical devices, microfluidics, and bonding technologies. The Casimir forces for flat bodies can be described by the Lifshitz theory that takes into account the actual measured optical properties of the interacting materials. However, for rough surfaces the problem is more complicated by the nonadditivity of the dispersion forces. In this talk I will review the current state of the problem with attention to be given for metallic systems, phase change materials, and poor conductors (promising for operation in severe environments) with respect to adhesion/bonding technologies and actuation dynamics of MEMS/NEMS.