Modified fluorescence decay and other collective effects in cold atoms coupled to a hollow-core photonic-bandgap fiber

Collective and correlated states of atoms and light have applications in metrology and quantum information processing that include superradiant lasing, generation of non-classical light, and quantum memories for photons. A shared optical mode can enhance the collective response of an atomic ensemble coupled to it by mediating interactions between the atoms [1]. Here, we experimentally study the radiative dynamics of laser-cooled caesium atoms confined inside a photonic-bandgap fiber with a ~7.5 um diameter hollow core. The atoms are excited with pulses (ranging in length from ~1 to ~100 ns) near the cycling transition of 6S1/2, F = 4 to 6P3/2 , F’ = 5. We observe a variety of atom-number and excitation pulse-detuning dependent effects in the forward and backward direction with respect to the propagation of the excitation pulse, including significantly reduced fluorescence lifetimes of the atomic ensemble.

[1]: J. Ruostekoski et al. Emergence of correlated optics in one-dimensional waveguides for classical and quantum atomic gases, PRL 117, 143602 (2016)

*This research was undertaken in part thanks to funding from the Canada First Research Excellence Fund's Transformative Quantum Technologies (TQT) initiative.