Theoretical Physics of Molecules and Quantum Systems

The AMOPP group has a number of theoretical research programs including:

• Theoretical molecular physics (Prof Jonathan Tennyson)
• Ultracold molecules and collisions (Prof Jonathan Tennyson)
• Atoms and molecules in intense laser fields (Dr Carla Figueira de Morisson Faria and Prof Jonathan Tennyson)

Please read below for more details.

Theoretical molecular physics

The molecular theory group develops methods based on first principles quantum mechanics for  studying the structure, spectra and collision properties of molecules. Research in the group is a  mixture of studying fundamental problems such as ultra cold molecular collisions and electron and positron molecule collisions, and application of theoretical methods to key areas such as astrophysics and atmospheric physics, where as part of the CAVIAR consortium we are trying to determine the physical basis of the so-called water continuum.

The image on the left shows an artists impression of extra solar planet HD189733b. Calculations by the molecular theory group led directly to the detection of water in the atmosphere of the hot Jupiter-like planet in 2007, the first molecule detected on an extra solar planet.

The molecular theory group also works alongside the Quantemol company producing software model electron polyatomic molecule interactions for a variety of applications including plasma physics.

Ultracold molecules and collisions

The formation of ultracold molecules is a new and rapidly developing area in the physics of quantum degenerate gases. The aim of our research is to theoretically understand the dynamics of the association of molecules and its interplay with the bulk motion in trapped Bose-Einstein condensates and quantum degenerate two component Fermi gases. The applications of our research are far reaching; they range from precise studies of two- and few-body ultracold collisions to the many-body physics of Cooper pairing of Fermions.

Our ongoing research includes topics such as:

• Molecular formation via magnetic field tunable interatomic interactions as well as photoassociation
• The description of atom-molecule coherence phenomena in Bose-Einstein condensates.
• The development of practical methods to describe Feshbach resonance enhanced diatomic collisions as well as two- and three-body bound states in the tight microtraps of optical lattices.

Atoms and molecules in intense laser fields

When atoms and molecules are exposed to extremely strong laser fields novel and exciting processes can take place. At UCL we have an ongoing program of experimental and theoretical work studying these processes such as above threshold ionization, high-order harmonic generation, electron recollision, and non-sequential double ionization. In recent years, understanding these processes has led to the possibility of using ultrashort laser pulses to image molecular processes on the attosecond timescale and the angstrom length scale simultaneously. The theory underpinning our understanding of these processes is being actively developed by Carla Faria, and Jonathan Tennyson is extending R-matrix methods to apply to these problems.