Thermal reduction of a two-mode squeezed vacuum
= Thermal reduction of a two-mode squeezed vacuum
{title2=$\rho_1=(1-q)\sum_{n\ge0}q^n|n\rangle\langle n|$}
Tracing out one mode leaves geometric occupation <probabilities> with $q=|\lambda|^2$. In an oscillator basis of <frequency> $\omega$, they are <Boltzmann weights> with $k_BT=\hbar\omega/\ln(1/q)$. The joint state can be pure while each reduced state is mixed.