# Condensed Matter Seminar: "Atom-Light Interactions in Slow-Light Waveguide QED"

Slow-light waveguide QED refers to a regime where the maximal photonic group velocity is significantly reduced compared to free space. Such conditions could be achieved in one-dimensional photonic periodic structures such as photonic crystals, coupled-resonator arrays, modulated fibres, etc. In this talk I will describe the main features of atom-light interactions in this slow-light regime.

In the first part I will discuss the bound states formed by an atom and a localized photonic excitation that represent the continuum analog of the familiar dressed states in single-mode cavity QED. The extension to the multi-photons and multi-atoms case is also considered.

In the second part I will describe the coupling of moving atoms to such slow-light waveguide in the regime where the atomic velocities are comparable to the effective speed of light. In this case, the interplay between a velocity-induced directionality and the emergence of new divergences in the photonic density of states gives rise to a range of novel phenomena and nonperturbative effects in the emission of photons and the resulting photon-mediated interactions between moving atoms.