When we set new records for coldest temperature in the universe, we usually do it with gases (see: https://physicsworld.com/a/millikelvin-cooling-of-large-molecules-is-no-myth/)

How do we pull this off without phase changes to liquid or solid? A phase diagram of Helium, for example, shows that Helium can only stay a gas until around 1K under special conditions. How do we pull off mK or nK?