A transient thermal cloak experimentally realized through a rescaled diffusion equation with anisotropic thermal diffusivity

Transformation optics has made a major contribution to the advancement of modern electromagnetism and related research assisted by the development of metamaterials. In this work, we applied this concept to the thermodynamics using the coordinate transformation to the time-dependent heat diffusion equation to manipulate the heat flux by predefined diffusion paths. Experimentally, we demonstrated a transient thermal cloaking device engineered with effective thermal materials and successfully hid a centimeter-sized vacuum cavity. A rescaled heat equation accounting for all the pertinent parameters of various ingredient materials was proposed to greatly facilitate the fabrication. Our results unambiguously demonstrate the practical possibility of implementing complex transformed thermal media with high accuracy and acquiring several unprecedented thermodynamic functions, which we believe will help to broaden the current research and pave a new path to manipulate heat for novel device applications.