Tailoring Casimir Forces and Torques Through Geometry and Optical Response

The confinement of quantum electromagnetic fluctuations between two macroscopic objects results in a force, i.e. the Casimir force, which draws the two objects closer together to minimize the energy of the system. This force depends on both the geometry and the optical properties of the materials involved. Here we present measurements of the Casimir force between two spheres – a geometry that has previously eluded measurement due to experimental difficulties. Further, a Casimir torque is thought to exist between two optically anisotropic materials. Here we will also describe how careful choice of dielectrics can enhance the predicted Casimir torque, making it within reach of current experiments.