Theory of deep minima in (e,2e) measurements of triply differential cross sections.

Deep minima in He(e,2e)He+ triply differential cross sections are traced to vortices in atomic wave functions. Such vortices have been predicted earlier, but the present calculations show that they have also been observed experimentally, although not recognized as vortices. Their observation in (e,2e) measurements shows that vortices play an important role in electron correlations related to the transfer of angular momentum between incident and ejected electrons. The vortices significantly extend the list of known features that summarize the general picture of electron correlations in impact ionization.

Creating and manipulating vortices in atomic wave functions with short electric field pulses.

We demonstrate the creation of vortices in the electronic probability density of an atom subject to short electric field pulses, how these vortices evolve and can be manipulated by varying the applied pulses, and that they persist to macroscopic distances in the spectrum of ejected electrons. This opens the possibility to use practical femtosecond or shorter laser pulses to create and manipulate these vortex quasiparticles at the atomic scale and observe them in the laboratory. Within a hydrodynamic interpretation we also show, since the Schrödinger equation is a particular instance of the Navier-Stokes equations, that for compressible fluids vortices can appear spontaneously and with a certain time delay, which is not expected to occur from the conventional point of view, illustrating applicability of the present study to vortex formation more broadly.

Origin, evolution, and imaging of vortices in atomic processes.

Vortices are usually associated with systems containing large numbers of particles. Of particular topical interest though are those formed within atomic-scale wave functions and observed in macroscopic systems such as superfluids and quantum condensates. We uncover them here in one of the most fundamental quantum systems consisting of just one electron and two protons. Moreover, the results of novel simulations of the dynamics of this system reveal previously unknown mechanisms of angular momentum transfer and new ways to image atomic-scale quantized vortices at macroscopic distances. Probing of vortices and vortex-driven dynamics in quantum systems is thereby illustrated.

Properties of pseudopotentials for higher partial waves.

Contact psuedopotentials for relative angular momentum greater than zero are of interest for the study of cold atomic gases. For bosons, it is known that when the s-wave scattering length becomes infinite, an infinite number of three-body bound states, called Efimov states, are predicted by such potentials. Realistic potentials also exhibit the such states, thus a study of the Efimov effect for contact psuedopotentials for higher partial waves and fermions is important for the study of cold atoms. In this Letter we analyze three-body states of three particles interacting via psuedopotentials for higher partial waves and show that there is an Efimov effect for three fermions interacting via p-wave psuedopotentials.

Regge oscillations in integral cross sections for proton impact on atomic hydrogen.

The integral cross sections for elastic scattering and spin exchange for proton impact on atomic hydrogen show several oscillations in the energy range 0.01-1.0 eV that cannot be associated with resonances or the glory effect. A complex angular momentum analysis using computed Regge trajectories shows that each peak of the oscillatory structure is predominantly associated with at most three trajectories. In this way, the peaks are related to the L=0 bound states of H+ 2. The complex angular momentum theory for integral cross sections that we introduce shows that such oscillations are a general feature of potential scattering.