= Quantum concentration
{title2=$n_Q=\lambda_T^{-3}=(mk_BT/(2\pi\hbar^2))^{3/2}$}
The translational concentration scale for a nonrelativistic particle in three dimensions, per internal state. It is the inverse cube of the <thermal de Broglie wavelength>. A classical component with number density $n$ and external one-particle energy $U$ has <chemical potential> $\mu=k_BT\ln(n/n_Q)+U$. An additional internal degeneracy must be included explicitly; it is not hidden in this definition. The dilute classical condition is $n/n_Q\ll1$ for each occupied internal component.
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