Squeezed electromagnetic vacuum does have a renormalized energy density smaller than the vacuum. So it makes it in my opinion a inconspicuous candidate for a dark energy carrier.

Are there observatories at the moment attempting to detect squeezed radiation from astrophysical and cosmic background sources? If not, What sort of equipment do you need to measure squeezed vacuum radiation?

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pretty interesting question, +1 –  lurscher Jul 17 '12 at 13:40
Why would the lower energy density of the squeezed vacuum make it a candidate for dark energy? –  kleingordon Jul 17 '12 at 17:02