How do we do experiments on gases at zero Kelvin?

Question

We say that at temperatures very close to absolute zero (nano or pico Kelvin) there is no gas, so how do we do experiments on gases at zero Kelvin, and why is Bose-Einstein described as a gas?

1995 – Eric Cornell and Carl Wieman create the first[14] Bose-Einstein condensate, using a dilute gas of Rubidium-87 cooled to 170 nK.

2015 - Experimental physicists at the Massachusetts Institute of Technology (MIT) successfully cooled molecules in a gas of sodium-potassium to a temperature of 500 nanokelvins.

Answer 1

For the technique of cooling and trapping, see https://www2.physics.ox.ac.uk/sites/default/files/2013-01-19/andrian_pdf_71380.pdf.

By the way, trapping is not only needed to thermally isolate the system and to further cool it with lasers after the Doppler effect, but also to allow the atoms to align themselves undisturbed to a BEC. Any contact with the walls of the experimental setup results in interactions of the magnetic dipoles of the atoms of the BEC with those of the walls. Since the atoms of the walls have chaotically distributed magnetic dipoles, a BEC would never come into being.

Yet another prediction. The choice of gas that can condense into a BEC also depends on the design of the magnetic trap with its intersecting magnetic fields. In principle, the possible "crystal" structure resulting from the existing magnetic dipoles of the gas atoms must be reflected by the MOT.