Probing amplified spontaneous emission to superradiance transition in cold Cs atoms inside a hollow-core photonic-crystal fiber*

We investigate the critical conditions to realize the transition from amplified spontaneous emission (ASE) to superradiance (SR) with an ensemble of laser-cooled Cs atoms inside a hollow-core photonic crystal fiber (HCPCF). In our experiment, the Cs atoms, initially cooled using a magneto-optical trap (MOT), are guided and confined inside a short piece of HCPCF with a magic-wavelength dipole trap. This work constitutes the preliminary elements of our current experimental investigations towards realization of an ultra-narrow linewidth superriant laser. Additionally, we aim to study long range coherence in atomic ensembles and explore the symmetries governing atom-field couplings in the HCPCF platform.