Master´s Thesis Defense by Mantas Cepulkovskis

In this thesis, a general formalism is developed to investigate effective nonlinear photon-photon interactions for a system of multiple quantum emitters coupled to a waveguide. Two-level quantum emitters and a weak input coherent state field incident on one of the sides of a 1D waveguide is considered. The input field propagates along the waveguide and interferes with the emitted photons, giving rise to a rich range of nonlinear effects. In particular, the second-order correlation function and nonlinear output intensity are calculated, both of which in this method are not restricted by the number and placement of the emitters, nor the combination of light-matter coupling constants, which may differ depending on the propagation direction. The introduced approach is then used to investigate robustness of chiral waveguides due to imperfections – the coupling to the suppressed propagation direction.