## Giacomo De Palma - D. Trevisan - V. Giovannetti

# Passive states optimize the output of bosonic Gaussian quantum channels

created by trevisan on 10 Jun 2017

[

BibTeX]

*preprint*

**Inserted:** 10 jun 2017

**Year:** 2015

**Abstract:**

An ordering between the quantum states emerging from a single mode
gauge-covariant bosonic Gaussian channel is proven. Specifically, we show that
within the set of input density matrices with the same given spectrum, the
element passive with respect to the Fock basis (i.e. diagonal with decreasing
eigenvalues) produces an output which majorizes all the other outputs emerging
from the same set. When applied to pure input states, our finding includes as a
special case the result of A. Mari, et al., Nat. Comm. 5, 3826 (2014) which
implies that the output associated to the vacuum majorizes the others.