Non-local correlations in quantum electrodynamics

Sakae Minami

Ioannis E. Antoniou, Evgueni Karpov, G. P. Pronko

Antony Valentini

Krishna Rai Dastidar

By considering a new, non-local quantum electrodynamics, wc have shown that the non-sequential double ionization of aloms occur due to the phase correlated two-photon excitation o f electrons.For this phase conelated excitation, two-photon rate depend.slinearly on laser intensity.However, the local nature of the radiation field gives rise to conventional multiphoton transitions, where the two-photon rate is proportional to the square of the laser intensity Wc have shown that n-photon transitions in an experiment can be modeled as a series o f these two types of transitions and hence several channels will run parallel to each other The channels for w-photon transitions are (i) a scries of phase correlated transitions giving rise to non-sequential double ionization, (ii) a senes of conventional dipole transitions giving rise to sequential ionization and (in) a mixture of phase correlated and phase non-corrclated transitions We have shown that, with the increase in laser intensity the channel comprising of only the phase correlated excitations becomes significant and gets saturated before the sequential channel can dominate, giving rise to a kink-like structure in the intensity variation of double inoi/ation 1 ins feature has been observed in the experiments on double ionization of He Wc have also provided a physical basis for the damping of non-sequcntial double inoization at the smaller wavelength, which is also an experimentally observed feature.

H.P. Tran

Krishna Rai Dastidar, T. K. Rai Dastidar

In a recent work [Mod. Phys. Lett A13, p-1265 (1998)] we expounded a non-local Quantum Electrodynamics (QED) which predicted a linear two-photon absorption by an atom placed in a laser field of appropriate intensity and frequency. In this paper we extend our earlier work to show that the theory allows for linear 2n-photon absorption by gaseous matter where, under suitable conditions, n may literally run upto thousands. The consequences of this extension of the theory are outlined and predictions are made which may be verified in laboratories.