Tracking Quantum Populations in Non-Sequential Double Ionization of Atoms

Krzysztof Sacha, Bruno Eckhardt

González Blázquez, María Isabel

Non-sequential double ionization (NSDI) is a strong-field process involving the correlated emission of two electrons. This thesis proposes an analog quantum simulator to study NSDI in a helium atom, using ultracold trapped atoms to represent electrons. The core potential is replaced by an optical trap created by a laser. Rydberg atoms, with their strong long-range interactions, are ideal for simulating attosecond phenomena. A numerical simulation is conducted to observe the correlated two-electron momentum components after a laser pulse is applied.

Zhifang Deng

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.

Giovanni P. Arrighini, Carla Guidotti, N. Durante

Anatoli S. Kheifets

We develop a formalism which describes sequential two-photon double ionization (TPDI) of a closed-shell atom. We apply this formalism to calculate the angular asymmetry parameters of sequential TPDI of the Ne 2p and Ar 3p valence subshells. Comparison with the latest experimental data is made.