2D ferroelectrics for nonlinear optics and topological defects

Photonic quantum computing is rapidly advancing as a field, and the latest demonstration of quantum supremacy using boson sampling is especially striking. For further scaling up, micron-size integration of such components on a chip is impossible with bulk crystals. Using nontraditional materials could deliver a revolution to the creation of entangled photons. We will grow ultrathin layered ferroelectrics such as SnS, and will also carry out calculations including a substrate to understand the ferroelectric coupling in few-layer SnS.

The strong non-linear optical properties of 2D ferroelectrics with in-plane intrinsic polarization could be integrated into waveguides to generate polarization-entangled photons fed by 2D QEs. Furthermore, the Berezinskii-Kosterlitz-Thouless (BKT) theory provides a paradigmatic example of phase transitions that are mediated by a change in the behavior of topological defect pairs. Low-dimensional ferroelectrics (FEs) support BKT transitions. In this phase, the condensation of vortices and anti-vortices substantially widens the technological resources of FEs. The aim of this research resides in the identification and characterization of such paired electric topological excitations, and understanding their optoelectronic properties.