Abstract:
Here I present two research subjects where many-body physics plays important roles in both of them. First is collective radiation from many atoms. This collective radiation involves superradiance and subradiance, which originates from multiple scattering of photons in the medium and manifests in collective energy shifts and line width broadening or shortening respectively. These very opposite phenomena are present in strong light-matter interacting systems, ranging from atoms, ions, molecules, and NV centers in diamonds.
Next I show some interesting results in one-dimensional (1D) quantum gas. When atom-atom interactions are strong enough, 1D bosonic particles tend to repel each other and behave like fermions. And as such, the density of spinor Bose gas has a broadened momentum distribution due to degenerate spin configurations and strong interactions. We further study strongly interacting fermions with SU(N) spin symmetry, which again manifests its effect in broadened momentum distributions. Both present one universality class of 1D quantum fluid with exponentially decayed correlations in space.