Pursuit of the Kramers-Henneberger atom

Ioksang Leung, Mingyu Zhu, P. X. Wang +1 more

Abstract The dichotomy structure is one of the prominent features of Kramers–Henneberger (KH) atoms. Within a focused laser field, the wave function of KH atoms becomes polarized due to ponderomotive (PM) forces induced by light intensity gradients, leading to the disruption of the dichotomy structure. In a Gaussian-focused laser field, the PM forces are negligible only along the optical axis. To maintain the dichotomy structure of KH atoms over a broader area, we compared the result of flattened Gaussian laser beams with Gaussian-focused laser beams. By calculating the wave functions of ground KH state hydrogen atoms at various radial and angular locations in the laser focusing plane, it was demonstrated that under suitable laser parameters, the dichotomy structure can be fully or partially preserved in flattened Gaussian laser beams. Through the dichotomy structure of KH atoms, we can verify the existence of KH atoms using interference fringes of multi-photon ionization signals.

Alan G. Mencher, Mendel Sachs, Robert A. Satten

Frank H. Read

Jun-Dong Xiang, Pingxiao Wang, Jiaxiang Wang +1 more

In intense field laser dressing of atoms, electrons follow the laser oscillation and undergo quiver motion just like free electrons but still weakly bound to the atomic core, thus forming a set of specific dressed states named Kramers-Henneberger (KH) states. For decades, it was widely believed that ground KH state hydrogen atoms in a circularly polarized laser field exhibit the symmetric structure of a perfect ring. But our study shows this is not a common structure because of the fact that KH atoms can only exist in intense laser fields which are practically focused laser beams. In focused laser field, KH state electrons have to experience the ponderomotive force, which might polarize the atom and reshape its structure. Only in a laser beam with small quiver amplitude and high frequency, can the symmetric circular structure be fully or partially preserved.

Jean Dalibard, Christophe Salomon

Min Li, Qi Wei

The Electric Stark effect of a Kramers-Henneberger (KH) state of hydrogen atoms in both linearly and circularly polarized laser fields is studied. For the ground KH state of H atoms with a small quiver amplitude, the quadratic Stark effect is observed. For a large quiver amplitude, the Stark effect is quadratic only in a weak electric field and quickly changes to linear as the electric field increases. The atomic structure of the KH state is very sensitive to the electric field and can be easily polarized. The huge polarizability and induced dipole moment are comparable to those of Rydberg atoms.