Magnetic Illusion: Transforming a Magnetic Object into Another Object by Negative Permeability

An object's magnetic signature plays an essential role in everyday life, being used as a material fingerprint in applications from medical imaging to credit cards to security scanners. Can this signature be suppressed and substituted with a different one, in a magnetic illusion? Yes, and this work shows how. Theory is validated by experimental demonstration of transforming a ferromagnet into a superconductor, to all appearance. The essential ingredient in the illusion is negative magnetostatic permeability, which is realized with tailored sets of currents. These results open possibilities in the control of magnetic fields.