| Trapping and guiding of particles and small objects near surfaces is of importance in several systems holding great technological promise. Such trapping is strongly influenced by Casimir-Polder (or retarded van der Waals) forces. The systems of practical interest, are typically not in thermal equilibrium; examples are Bose-Einstein condensates, cold molecules and Rydberg atoms. Out-of equilibrium systems deviate substantially in behaviour from equilibrium ones. We consider in particular two effects of non-equilibrium: surprising behaviour with varying temperature, and enhanced forces due to interaction with geometrical resonances. In the latter case, dependence on the material properties of the surrounding geometry is emphasized. |
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