You use lasers to optically trap and cool the atoms, you can get them insanely cold very reliably with methods like this: https://en.wikipedia.org/wiki/Optical

You use lasers to optically trap and cool the atoms, you can get them insanely cold very reliably with methods like this: https://en.wikipedia.org/wiki/Optical_molasses https://en.wikipedia.org/wiki/Optical_molasses https://en.wikipedia.org/wiki/Polarization_gradient_cooling https://en.wikipedia.org/wiki/Polarization_gradient_cooling https://en.wikipedia.org/wiki/Doppler_cooling https://en.wikipedia.org/wiki/Doppler_cooling The components in a system like this are probably operating at room temperature.