Beam splitter as quantum coherence-maker

Abstract

The aim of this work is to answer the question of how much quantum coherence a beam splitter is able to produce. To this end, we consider as the variables under study both the amount of coherence of the input states as well as the beam splitter characteristics. We conclude that there is an optimal combination of these factors making the gain of coherence maximum. In addition, the two-mode squeezed vacuum arises as the studied state most capable of gaining coherence when passing through a beam splitter. These results are qualitatively equivalent for the l1-norm of coherence and the relative entropy of coherence.