Stark Effect Of Kramers-henneberger Atoms

With the improvement of super-intense lasers technology,laser field has reached peak intensity of 1022 W/cm2 and is expected to climb further in the future.High frequency superintense laser facilities include the free-electron laser in Hamburg,Germany and the Linac Coherent Light Source in Stanford,California.One of the most exotic perspective for atoms subjected to superintense high-frequency laser field is atomic stabilization against ionization,which means ionization decreases as the laser intensity increases.This counterintuitive phenomenon is attributed to the new effective binding potential between nucleus and the rapid oscillating electron driven by superintense laser field.For an atom exposed to strong laser fields,electrons will follow laser and do oscillation.The new Coulomb potential between electron and nucleus averaged over an oscillation cycle is called “Kramers-Henneberger”(KH)potential.High Frequency Floquet Theory(HFFT)shows that in high-frequency limit,KH potential can support many stable bound eigenstates and those states are called KH states and the corresponding atom is called KH atom.The unique prospect of KH atom has fostered many theoretical works in the past decades.In this thesis,we study Stark effect of ground KH state hydrogen atom in both linearly and circularly polarized laser fields.We study how external electric field changes structure and energy levels of KH atoms.We evaluate Stark energy and induced dipole moment as well as polarizability.Similarities between KH atoms and Rydberg atoms are also discussed.In linearly and circularly-polarized laser field,at small quiver amplitude,Stark effect of ground KH state hydrogen atom is quadratic during the whole range of electric field of interest;At large quiver amplitude,Stark effect of ground KH state hydrogen atom starts with second order and changes to first order as external electric field increases.In both linearly and circularly-polarized laser field,polarizabilities of ground KH state hydrogen atom are functions of quiver amplitude.These properties of KH atoms are very similar toatoms in highly excited states,like Rydberg atoms.