Can someone please explain this concept for me? As I understand

[Carnot]

Can someone please explain this concept for me?

As I understand it, you have a, let's say, a three-level atom with two hyperfine states and an excited state. Then you apply a pump source (perhaps a laser) to transfer the atom from one of the hyperfine states (say |g1>) to the excited state. After applying the first laser, another laser source is applied to get the atom down to the second hyperfine state (|g2>).

I don't quite get this last step. How do you transfer the atom down to a lower energy level by applying a laser source? By stimulated emission?

 

[SpectraCat]

Can someone please explain this concept for me?

As I understand it, you have a, let's say, a three-level atom with two hyperfine states and an excited state. Then you apply a pump source (perhaps a laser) to transfer the atom from one of the hyperfine states (say |g1>) to the excited state. After applying the first laser, another laser source is applied to get the atom down to the second hyperfine state (|g2>).

I don't quite get this last step. How do you transfer the atom down to a lower energy level by applying a laser source? By stimulated emission?

Exactly. You tune the "dump" laser so that it matches the transition between the excited state and |g(2)>. If |g(2)> is initially empty, then you can assume the action of the second laser will be to transfer population from the excited state to |g(2)>. However if |g(2)> is has a significant population, then you cannot assume the second laser will only "dump" population, since it could also "repump" population from |g(2)> back up to the excited state.