3 ms·
You can go a bit lower than the temperature of liquid helium just as you can cool something to lower than the temperature of liquid water just by using evaporat
by fjorder 14y ago
You can go a bit lower than the temperature of liquid helium just as you can cool something to lower than the temperature of liquid water just by using evaporating water. However, 4 Kelvin is probably correct. The image they show appears to be of a cryostat that would almost certainly use helium as a cryogen. Such cryostats are realistically limited to around 2-3 Kelvin. They can go a bit lower when empty, but generally not if you stick a complex experiment with a lot of heat-conducting fibers and wires into them.
4K is probably warmer than they'd like for a quantum circuit, but getting their apparatus colder would require a much beefier cryostat or more exotic technologies like magnetic cooling built inside a helium cryostat. Such setups are capable of getting complex setups down to the hundreds of millikelvin, which is much nicer for this sort of work!
As for writing a scientific article using Fahrenheit... Please don't do that. Just don't.
- ars 14y agoWell obviously you can go lower, but 4K is the boiling point of Liquid Helium, so it's the easiest temperature to hold it at. In the article they mention they chip itself is kept at millkelvin temperatures. And I disagree about using Fahrenheit - this is not a paper in a journal, it's a lay article. By all means use Fahrenheit if that's what your audience understands. Don't let pedantry get in the way of clarity. (Kelvin has some real meaning, but C vs F is totally arbitrary. One is the freezing point of water, the other is the lowest temperature you can get with a salt/ice mixture.)