Radiative heat transfer and noncontact friction between nanostructures

All material bodies are surrounded by a fluctuating electromagnetic field because of thermal and quantum fluctuations of the current density inside them. A general formalism for the calculation of the spectrum of fluctuations of this electromagnetic field is presented and applied to the radiative heat transfer and van der Waals friction. The radiative heat transfer and the van der Waals friction are greatly enhanced at short separations ($d\ll\lambda_T=c\hbar/k_BT$) between the bodies due to evanescent electromagnetic waves. Particularly strong enhancement occurs if the surfaces of the bodies can support localized surface modes such as surface plasmons, surface polaritons, or adsorbate vibrational modes. Electrostatic and phonon mechanisms of noncontact friction are also discussed. The theory is compared with the experimental results.