Gravitational lensing and tunneling of mechanical waves in synthetic curved spacetime

Black holes are considered among the most fascinating objects that exist in our universe since in the classical formalism nothing, not even light, can escape from their vicinity due to gravity. The gravitational potential causes the light to bend toward the hole, which is known as gravitational lensing. Here, we present a synthetic realization of this phenomenon in a laboratory-scale two-dimensional network of mechanical circuits, based on analogous condensed matter formalism of Weyl semimetals with inhomogeneous nodal tilt profiles. Some of the underlying network couplings turn out as unstable and nonreciprocal and are implemented by embedded active feedback interactions in an overall stabilized structure. We demonstrate the lensing by propagating mechanical wave packets through the network with a programed funnel-like potential, achieving wave bending toward the circle center. We then demonstrate the versatility of our platform by reprogramming it to mimic quantum tunneling of particles through the event horizon, known as Hawking radiation, achieving an exceptional correspondence to the original mass loss rate within the hole. The network couplings and the potential can be further reprogrammed to realize other curvatures and associated relativistic phenomena.