Chiral Casimir Forces: Repulsive, Enhanced, Tunable

Understand

Both theoretical interest and practical significance attach to the sign and strength of Casimir forces.

• A famous, discouraging no-go theorem states that "The Casimir force between two bodies with reflection symmetry is always attractive." Here we identify a loophole in the reasoning, and propose a universal way to realize repulsive Casimir forces.
• We show that the sign and strength of Casimir forces can be adjusted by inserting optically active or gyrotropic media between bodies, and modulated by external fields.