Author here. Yes, Doppler Cooling is the first step used in the experiment, in a Magneto Optical Trap [0]. It is followed by Polarization Gradient Cooling [1] t

Author here. Yes, Doppler Cooling is the first step used in the experiment, in a Magneto Optical Trap [0]. It is followed by Polarization Gradient Cooling [1] to overcome the Doppler limit. Atoms are still way too "hot" after this step, so they are then transferred to a purely magnetical trap and cooled down further via forced evaporation [2]. [0] https://en.wikipedia.org/wiki/Magneto-optical_trap https://en.wikipedia.org/wiki/Magneto-optical_trap [1] https://en.wikipedia.org/wiki/Sisyphus_cooling https://en.wikipedia.org/wiki/Sisyphus_cooling [2] https://en.wikipedia.org/wiki/Evaporative_cooling_(atomic_physics) https://en.wikipedia.org/wiki/Evaporative_cooling_(atomic_ph...