  Quantum electronic noise, the random current fluctuations generated by
electrons crossing a quantum conductor, has been thoroughly studied from the
electron point of view. Recent experiments have shown that such noise may have
striking properties in terms of the quantum electromagnetic field it generates.
Both the existence of vacuum squeezing \cite{PAN_squeezing} and generation of
correlated photon pairs \cite{C4quantique} have been observed. Here we
demonstrate that this electromagnetic field also violates Bell-like
inequalities, thereby proving its true quantum nature. This is achieved by the
observation of two-mode quadrature squeezing of vacuum: the electromagnetic
field quadratures at two different frequencies can be so correlated that their
difference goes below vacuum fluctuations. Thus, electronic noise contains
entangled photon pairs, a key ingredient for quantum computing and
communication.
