Can you explain the fugacity of boson gas in Bose-Einstein Condensation?

[Ang Han Wei]

Hi,
my course just provided an introduction to Bose-Einstein Condensation.

I was told that this phenomenon occurs when the temperature of Bosons go under a certain critical temperature $T_{c}$ > 0K. At absolute zero, all the Bosons go into the condensed phase.

However, at temperatures between 0K and $T_{c}$, there is a mixture of an ideal Boson gas and condensed bosons.

What then is the fugacity of the boson gas in such an instance?

 

[DrDu]

The chemical potential is exactly 0, which corresponds to fugacity 1, I suppose. Hence the density of non-condensed bosons becomes a function of T, only for T<Tc.