Would one rather store squeezing or entanglement in continuous variable quantum memories?

Given two quantum memories for continuous variables and the possibility to perform passive optical operations on the optical modes before or after the storage, two possible scenarios arise resulting in generally different degrees of final entanglement. Namely, one could either store an entangled state and retrieve it directly from the memory, or rather store two separate single-mode squeezed states and then combine them with a beam-splitter to generate the final entangled state. In this Letter, we analytically determine which of the two options yields more entanglement for several regions of the systemʼs parameters, and quantify the advantage it entails.

► We study the optimised storage of continuous variable entanglement. ► Analytical conditions to determine optimal storage schemes. ► Comprehensive numerical studies complementing the analytics. ► Specific discussion concerning QND feedback memories included. ► Results applicable to very general Gaussian channel.