Cooling and (or?) heating ion trap experiments

[rwooduk]

I'm currently studying ion trap experiments, many papers suggest the cooling of trapped ions, and other papers say its a heating process. I know there's a difference as to what each refers but am unclear of the difference. I'll quote:

The interaction of fluctuating electric fields with the motional state of the ion leads to heating and thus to decoherence for entanglement generation limiting the fidelity of quantum logic gates. Effective ground state cooling of trapped ion motion and suppression of motional heating are thus crucial to many applications of trapped ions in quantum information science.

http://iontrap.umd.edu/wp-content/uploads/2013/10/Thesis_2006_Deslauries.pdf

Please could someone shed some light on how heating and cooling differ in this statement? What is heated, what is cooled? do both occur at the same time?

Thanks for any ideas.

 

[DrClaude]

A trapped ion will slowly be heated due to the presence of noise in the trapping electric potential. Cooling is achived using external means. If you look at the table of contents of the thesis you linked to, you will see a chapter on the use of laser cooling to that effect.