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A recent experiment with squeezed light has shown that two-photon absorption by an atom can occur with a linear intensity dependence. We point out that this result verifies a prediction made by us a decade back from an analysis of a non-local model of Quantum Electrodynamics. This model had earlier been proposed by us in an ad hoc manner to interpret certain features of multiphoton double ionisation and above-threshold ionisation in an atom placed in a strong laser field ; in this paper we show that the model can be obtained field-theoretically by demanding covariance of the field Lagrangian under a nonlocal U(1) gauge transformation. We also show that the model makes direct contact with squeezed light, and thus allows us to describe these two completely different scenarios from a unified point of view. We obtain a fundamentally new result from our non-local model of QED, namely that only the past, but not the future, can influence the present -thus establishing a non-thermodynamic arrow of time. We also show that correlations within a quantum system should necessarily be of the Einstein-Podolsky-Rosen (EPR)-type, a result that agrees with Bell's theorem. These results follow from the simple requirement of energy conservation in matter-radiation interaction. Furthermore, we also predict new and experimentally verifiable results on the basis of our model QED.

A nonlocal gauge symmetry of a complex scalar field, which can be trivially extended to spinor fields, was demonstrated in a recent paper (Mod. Phys. Lett. A13, 1265 (1998), hep-th/9902020). The corresponding covariant Lagrangian density yielded a new, nonlocal quantum electrodynamics. In this letter we show that as a consequence of this new QED, a black body radiation viewed through gaseous matter appears to show a slight deviation from the Planck formula, and propose an experimental test to check this effect. We also show that a non-uniformity in this gaseous matter distribution leads to an (apparent) spatial anisotropy of the black body radiation. *

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