If black holes have a finite entropy, they should also have a finite temperature.
In any real system at finite temperature there are processes which cause a scrambling of the phase of the quantum states.
So a black hole can only be in equilibrium with a gas of radiation at a finite temperature.
However, for general strongly interacting plasmas at finite temperatures, other methods based on, say, density functional theory, are needed.
A generalization to finite temperature is also available.
This has been shown to be a useful tool in studying the behavior of quantum field theories at finite temperature.
That and the fact that it melts at a finite temperature.
The trapped components are referred to as the 'ambient plasma' and will later be allowed to have finite temperature.
At finite temperature, a closed expression for noise can be written.
At finite temperatures a thermal average over is implicit.