Confidential Direct Communications: A Quantum Approach Using Continuous Variables

We consider the problem of privacy in direct communications, showing how quantum mechanics can be useful to guarantee a certain level of confidentiality. In particular, we review a continuous variable approach recently proposed by us [Pirandola
et al.
,
Europhys. Lett.
, vol. 84, pp. 20013-1-20013-6, 2008]. Here, we analyze the degree of privacy of this technique against a broader class of attacks, which includes non-Gaussian eavesdropping.