  Beam splitters are routinely used for generating entanglement. Their
entangling properties have been studied extensively, with nonclassicality of
the input states a prerequisite for entanglement at the output. Here we
quantify the amount of entanglement generated by weakly-reflecting beam
splitters, and look for nonclassical states that are not entangled by general
beam splitters. We find that inputting highly nonclassical combinations of
unpolarized states that are squeezed and displaced onto a beam splitter can
still yield separable output states. This result is crucial for understanding
the generation of modal entanglement by beam splitters.
