Positronium Laser Cooling via the 1^{3}S-2^{3}P Transition with a Broadband Laser Pulse.

We report on laser cooling of a large fraction of positronium (Ps) in free flight by strongly saturating the 1^{3}S-2^{3}P transition with a broadband, long-pulsed 243 nm alexandrite laser. The ground state Ps cloud is produced in a magnetic and electric field-free environment. We observe two different laser-induced effects.

Production of positronium chloride: A study of the charge exchange reaction between Ps and Cl.

We present cross sections for the formation of positronium chloride (PsCl) in its ground state from the charge exchange between positronium (Ps) and chloride (Cl-) in the range of 10 meV-100 eV Ps energy. We have used theoretical models based on the first Born approximation in its three-body formulation. We simulated the collisions between Ps and Cl- using ab initio binding energies and positronic wave functions at both the mean-field and correlated levels extrapolated to the complete basis set limit.

Quantum-Path-Resolved Attosecond High-Harmonic Spectroscopy.

Strong-field ionization of molecules releases electrons which can be accelerated and driven back to recombine with their parent ion, emitting high-order harmonics. This ionization also initiates attosecond electronic and vibrational dynamics in the ion, evolving during the electron travel in the continuum. Revealing this subcycle dynamics from the emitted radiation usually requires advanced theoretical modeling.

High complexity femtosecond pulse duplicator.

This paper presents a theoretical and numerical study of a 0-π fan-out phase grating placed in the Fourier plane of a spatio-spectral pulse shaper followed by a spherical focusing lens. It is shown that this device acts as a high complexity femtosecond pulse duplicator designed for two source interferometry. At the focus of the lens, the electric field displays two spatially separated intense spots in which relative delay can be continuously tuned over 4 orders of magnitude, typically from a few attoseconds to a few tens of femtoseconds.