Optical implementation of Riemann sheets: an analogy to an electromagnetic 'wormhole'.

Inspired by the branch cut that can link two Riemann sheets in complex function theory, we utilize the branch cut to mimic an electromagnetic 'wormhole' linking two 2D 'parallel spaces' in a reference space. With the help of optical conformal mapping, we design a time-varying inhomogeneous medium that can effectively perform like an electromagnetic 'wormhole' in the real space. Based on this method, we can simulate the evolutionary process of an electromagnetic 'wormhole' and the wave propagation from one space to another in a laboratory environment. The proposed device may also be applied in light capture, light modulators, and absorption with directional dependence.