  We study how photon absorption losses degrade the bipartite entanglement of
entangled states of light. We consider two questions: (i) what state contains
the smallest average number of photons given a fixed amount of entanglement?
and (ii) what state is the most robust against photon absorption? We explain
why the two-mode squeezed state is the answer to the first question but not
quite to the second question.
