Multimode quantum entropy power inequality

The quantum version of a fundamental entropic data-processing inequality is presented. It establishes a lower bound for the entropy that can be generated in the output channels of a scattering process, which involves a collection of independent input bosonic modes (e.g., the modes of the electromagnetic field). The impact of this inequality in quantum information theory is potentially large and some relevant implications are considered in this work.

Figure 1

Graphical representation of the scheme underlying the multimode QEPI (10): it establishes a lower bound on the von Neumann entropy emerging from the output port indicated by ${\mathbf{R}}_Y$ of a multimode scattering process that linearly couples $K$ independent sets of bosonic input modes (each containing $n$ modes), initialized into factorized density matrices.