"Phys.org) ?In the strange world of quantum mechanics, the vacuum
> state (sometimes referred to as the quantum vacuum, simply as the
> vacuum) is a quantum system's lowest possible energy state. While not
> containing physical particles, neither is it an empty void: Rather,
> the quantum vacuum contains fluctuating electromagnetic waves and so-
> called virtual particles, the latter being known to transition into
> and out of existence. In addition, the vacuum state has zero-point
> energy ? the lowest quantized energy level of a quantum mechanical
> system ? that manifests itself as the static Casimir effect, an
> attractive interaction between the opposite walls of an
> electromagnetic cavity. Recently, scientists at Aalto University in
> Finland and VTT Technical Research Centre of Finland demonstrated the
> dynamical Casimir effect using a Josephson metamaterial embedded in a
> microwave cavity. They showed that under certain conditions, real
> photons are generated in pairs, and concluded that their creation was
> consistent with quantum field theory predictions."
>
>
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Is this not a parametric amplifier?
Mark L. Fergerson