Condensate fraction
= Condensate fraction
{title2=$f_0=N_0/N$}
The <condensate fraction> is the population $N_0$ of a macroscopically occupied <one-particle state> divided by the total particle number $N$. For an interacting system, use a macroscopic <eigenvalue> of the one-particle <density matrix>, rather than assume that the relevant mode is an undeformed single-particle trap <ground state>. The <condensate fraction> is not generally the fraction measured as <superfluid> by a flow or rotation response.