Michael Spanner

Anatomy of strong field ionization

Strong field ionization is a starting point for a rich set of physical phenomena associated with attosecond u2009science. This paper provides an introductory overview of the basic theory of strong field ionization and focuses on (i) the physics and the dynamics of the electron transition to the continuum, and (ii) the shape of the electron wavepacket as it appears in the continuum.

Reading diffraction images in strong field ionization of diatomic molecules

We present a theoretical analysis of how intense, few-cycle infrared laser pulses can be used to image the structure of small molecules with nearly 1 fs temporal and sub-A spatial resolution. We identify and analyse several physical mechanisms responsible for the distortions of the diffraction image and describe a recipe for recovering an un-distorted image from angle and energy-resolved electron spectra. We also identify holographic patterns in the photoelectron spectra and discuss the requirements to enhancing the hologram resolution for imaging the scattering potential.

Two-pulse alignment of molecules

Field-free alignment of gas-phase molecules can be achieved by creating rotational wavepackets with a short laser pulse. We demonstrate that the degree of alignment can be improved by illuminating the molecules with a second laser pulse at a specific time during the evolution of the original rotational wavepacket.

Tunable optimal compression of ultrabroadband pulses by cross-phase modulation

We show how cross-phase modulation between two pulses, combined with optimal pulse shaping at the input of a dielectric medium, can be used to generate nearly single-cycle pulses that are tunable from the ultraviolet to the mid-infrared at the output of the medium, precompensating for dispersion to all orders.

Quantum logic in coarse grained control of wavepackets

We describe ‘coarse-grained’ control of wavepackets with finite resolution in phase space and show how this control can be approached as quantum information processing. To this end, we introduce the wavepacket analogues of qubits, designed to represent the information recorded within a wavepacket, and show how they can be addressed within a single wavepacket. The control is implemented both for non-dispersive wavepacket propagation using linear optical elements, illustrated for the classical waves, and for the dispersive evolution using fractional wavepacket revivals and AC Stark shifts as control tools, illustrated for the revivals of molecular alignment.