▎ 摘　　要

The Casimir force between neutral plates is attractive. For the Casimir force to be really useful one must be able to switch from attraction to repulsion. Exploiting the experimentalist's ability to change the sign of the charge carriers in graphene, we show how the sign of the Fresnel reflection coefficients can be reversed. This gives rise to a Casimir force between a metal sheet and graphene, which can be either attractive or repulsive; we illustrate it for a dielectric cylinder and graphene sheet. (C) 2014 Optical Society of America