Non-Hermitian Wave Transport with Spatio-Temporal Symmetries

The manipulation and management of wave propagation using artificial structures with tailored impedance profiles was always an exciting subject – often challenging the creativity of the researchers and exciting the imagination of the public. Throughout the years, many successful stories, that follow this line of research, have been reported: photonic crystals, negative index materials and transformation optics are some testaments of our increasing capabilities to manipulate the impedance profile of the underlying material. Currently however, an alternate viewpoint is emerging: Its focus is to manipulate the loss within the propagating medium and via a judicious design of the impedance profile to implement non-Hermitian symmetries in the wave structures. The surprising element is that it elevates the loss – an element which until recently was considered an “anathema”- to a useful design element whose manipulation can lead to the realization of devices with non-conventional properties and novel functionalities. Along these lines parity-time symmetric systems have been the tip of the spear for these new developments. In this talk, we will highlight some of these results, paying particular attention to some specific applications like hypersensitive sensors, enhanced emissivity, and energy harvesting where our group where our group is currently focusing its effort.