Ionization of oriented Rydberg states by subpicosecond half-cycle electromagnetic pulses

RYDBERG WAVEPACKETS IN MOLECULES: From Observation to Control

▪ Abstract  Significant advances in laser technology have led to an increasing interest in the time evolution of Rydberg wavepackets as a means to understanding, and ultimately controlling, quantum phenomena. Rydberg wavepackets in molecules are particularly interesting as they possess many of the dynamical complications of large molecules, such as nonadiabatic coupling between the various degrees of freedom, yet they remain tractable experimentally and theoretically. This review explains in detail how the method of interfering wavepackets can be applied to observe and control Rydberg wavepackets in molecules; it discusses the achievements to date and the possibilities for the future.

Active control of the dynamics of atoms and molecules

There has been much progress in the control of chemical reactions since methods of active control were first proposed by Brumer & Shapiro and by Tannor & Rice ten years ago. This chapter reviews both theoretical and experimental advances in the field. Control schemes based on quantum mechanical interference between competing paths and the manipulation of wave packets with tailored laser pulses are discussed. The theory of optimal control, the limitations of control theory applied to many-body dynamics, and the effects of constraints on the trajectory of the controlled observable are presented. Experimental progress in controlling the population of specific quantum states, in manipulating the dynamics of bound wave packets, and in the control of chemical reactions are reviewed, and current problems in the field are summarized.

Extension of the mapped Fourier method to time-dependent problems

A numerical method is described for integration of the time-dependent Schrödinger equation within the presence of a Coulomb field. Because of the singularity at r=0, the wave packet has to be represented on a grid with a high density of points near the origin; at the same time, because of the long-range character of the Coulomb potential, the grid must extend to large values of r. The sampling points are chosen, following E. Fattal, R. Baer, and R. Kosloff [Phys. Rev. E 53, 1217 (1996)], using a classical phase space criterion. Following those workers, the unequally spaced grid points are mapped to an equally spaced grid, allowing use of fast Fourier transform propagation methods that scale as N ln N, where N is the number of grid points. As a first test, eigenenergies for the hydrogen atom are extracted from short-time segments of the electronic wave-packet autocorrelation function; high accuracy is obtained by using the filter-diagonalization method. As a second test, the ionization rate of the hydrogen atom resulting from a half-cycle pulse is calculated. These results are in excellent agreement with earlier calculations.