Nanomaterials are intriguing structures for quantum optics. Their color depends on their size and shape; they are very selective in the wavelengths they absorb and emit. Although nanostructures have been used to color windows and surfaces since the Middle Ages, we lack the understanding how size, shape, and microscopic structure control the optical properties of nanomaterials. In this project, we plan to develop a fundamental description of quantum optics in one-dimensional nanosystems. Core concepts will be quantum confinement and electron interactions when carriers are forced into a small space. The proposed work will focus on carbon nanotubes as a model nanosystem. The tubes show pronounced confinement effects; they emit and absorb light in the near infrared and visible. We will measure optical transitions, quantum cross sections, and electron interaction using luminescence, Raman scattering, and photoconductivity. The optical properties will be tailored by selecting specific tube types and changing the tube environment. A description of optical processes is incomplete without considering defects in real nanostructures. We will develop techniques to study and introduce imperfections. Their optical signatures and their effect on light emission will be determined on individual tubes. The experiments will be complemented by materials modeling. We will describe confinement effects and Coulomb interaction in semiempirical calculations of nanotube light absorption. The knowledge gained on carbon nanotubes will be applied to predict and study the optical properties of other one-dimensional systems. The goal is to obtain a robust and transferable model of quantum optics in nanostructures. This project will also advance characterization of nanomaterials by optical spectroscopy and applications of nanotubes as light detectors and emitters. We plan to develop tools for nanotube population analysis (tube type) and to test carbon tubes as wavelength-selective photodetectors