A new magneto-optical trap for cold rubidium atoms in hollow-core fibres

As the second quantum revolution is reaching full maturity, more and more applications of quantum objects are being developed in the field now known as quantum technologies. The objective of my work was in fact to realise an experimental setup to cool and trap rubidium (Rb) atoms: first via a Magneto-Optical Trap (MOT), then inside a Hollow-Core Photonic-Crystal Fibre (HCPCF). The final aim is to demonstrate the possibility of delivering these atoms through a HCPCF with one end inside the vacuum chamber and the other (sealed) far from it, to use them for magnetometry or accelerometry applications. While doing so, the interaction of light with the atoms confined in the fibre also has to be studied. My work was devoted to the assembling of the Ultra-High Vacuum (UHV) setup hosting the MOT, and the laser system necessary to interact with the atoms. The latter was fully realised in-house, using only fibre components to make it more compact, easily operable and maintainable. Both target tasks were successfully achieved. The vacuum chamber can reach stable pressures ≃8×10^−10mbar. The laser setup is capable of delivering up to ≃40mW of optical power at 780nm, with line-width ≃0.6MHz. These values were also proven to be functional by effectively achieving MOTs of ≃8×10^7 atoms in a consistent way. Future prospects for my work will be to finalise a “conveyor belt” dipole trap setup, to trap the atoms from the MOT without magnetic fields, and move them directly inside the HCPCF. Subsequently, the physical processes relative to the atom-light interactions in the quasi-1D confinement of the fibre core can be studied. Quantum sensing measurements with atoms, both in free-space and within the fibre, can also be performed.