Nonclassical states that generate zero entanglement with a beam splitter

TL;DR

This paper investigates the conditions under which nonclassical input states to beam splitters do not produce entanglement, revealing that certain highly nonclassical states can yield separable outputs, which is important for quantum information processing.

Contribution

It identifies nonclassical states that do not generate entanglement through beam splitters, challenging the assumption that nonclassicality always leads to entanglement.

Findings

Highly nonclassical states can produce separable outputs

Squeezed and displaced unpolarized states may not generate entanglement

Quantifies entanglement generation by weakly-reflecting beam splitters

Abstract

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.