On atomic scales, this process can be carried out with laser trapping, as demonstrated by Steven Chu.
One method of carrying out this action was developed by London, Clark, and Mendoza and relies on the fact that a mixture of helium-3 and helium-4 undergoes phase separation. Because the magnetic field times the differential mangetization contributes a term to the thermodynamic relation, it is possible to carry out this process by reducing the magnetic field at constant entropy. A non-ideal gas for which the slope of the inversion curve is negative will undergo this process if constricted at constant enthalpy, a phenomenon known as the Joule-Thomson effect. On atomic scales, this process can be carried out with laser trapping, as demonstrated by Steven Chu. For ten points, identify this process which can also be achieved by running a Carnot heat engine in reverse, the lowering of a substance's temperature.
One method of carrying out this action was developed by London, Clark, and Mendoza and relies on the fact that a mixture of helium-3 and helium-4 undergoes phase separation.
cooling [accept equivalents like lowering of temperature and refrigeration]