Stability of atomic and molecular systems in strong external fields

Two projects are studied in this thesis: (1) Atomic and Molecular Stabilization in Super-Intense High-Frequency Laser Fields. (2) Entanglement of Dipole Arrays in External Electric Fields. Chapter 1 presents a general introduction and the motivation for these two projects. Chapter 2 focuses on atomic stabilization of negative multiple charged onions in linearly polarized super-intense high-frequency laser field in 3-dimensional space using both frequency independent (Section 2.2) and dependent (Section 2.3) potentials. By theoretical calculation, it is predicted that He-, He2-, Li- and Li2- are stable in super-intense high-frequency laser field. Chapter 3 studies atomic stabilization in both linearly and circularly polarized super-intense high-frequency laser field in both 3 dimensional space and large-D limit. Chapter 4 studies stabilization of simple diatomic molecules in linearly polarized super-intense high-frequency laser field in both 3 dimensional space and large-D limit. It was proved, in chapter 3 and 4, that dimensional scaling, combined with the High-Frequency Floquet theory, provides a useful means to evaluate the stability of gas phase atomic anions in a superintense laser field. Chapter 5 focuses on He-He bonding in linearly polarized super-intense high-frequency laser field. The distribution of the vibronic transitions from electric ground state to A1S+u excited state for He2 in superintense high frequency laser fields is obtained by numerical methods. Chapter 6 studies entanglement of multi-dimensional systems of dipoles in external electric fields. A new entanglement switch of qubits consisting of electric dipoles oriented along or against an external electric field and coupled by the electric dipole-dipole interaction is proposed in this chapter. The pairwise entanglement can be tuned and controlled by the ratio of the Rabi frequency and the dipole-dipole coupling strength. Tuning the entanglement can be achieved for one, two and three-dimensional arrangements of the qubits. The feasibility of building such an entanglement switch is also discussed in this chapter.