AtMol Research Seminar Archive
Index Current Seminars

Easter Term 2005

Date Speaker Home
The Delta-Kicked Rotor
April 27th Dr Phil Jones University College London
Laser and Electron Interactions with Atoms. Excitation, Ionization, Trapping and Manipulation
May 18th Dr Andrew Murray University of Manchester

In this talk I will describe various new laser based projects being carried out in the Atomic Physics group at Manchester. The group has specialised for many years in low energy electron interactions with atomic and molecular targets. Recent work has opened up this area to include laser interactions, where the target is either excited initially by the laser radiation prior to excitation or ionization by an electron beam, or an electron excited target is probed using resonant laser radiation. In both types of experiments, the very high resolution of the laser radiation and its coherence are exploited to provide new details on the interaction process which cannot be obtained using either technique alone.

New work has also begun on laser trapping of atoms in a Magneto Optical Trap following slowing of an atomic beam in a Zeeman slower. These trapped atoms will be further cooled to form a Bose Einstein Condensate, at which time electron impact experiments will commence from the coherent atomic ensemble. New information on both the interaction process, and on the BEC itself will then be produced.

Finally I will describe new experiments using chromium atoms which are laser collimated and manipulated onto surfaces for the production of nano-structures.

Construction of a Cold Atom Interferometric Gravimeter and First Results
May 19th Mr Patrick Cheinet Observetoire de Paris

12:00 pm in Ph327

Cavity QED at the Cutting Edge
May 25th Prof Mohamed Babiker University of York

4:15 pm in Ph30

Deterministically Controlled Emission of Photons from a Single Ion
June 1st Prof Wolfgang Lange University of Sussex

The controlled production of single photons from a single emitter is a process of fundamental importance for the manipulation of quantum states of light. It provides a coherent interface between the internal quantum states of an atom and propagating photonic states. At the Max-Planck Institut für Quantenoptik, we have localized a single calcium ion in a linear radiofrequency trap and coupled it to the electromagnetic field of an optical resonator. With fluctuations of the ion-field interaction below 2%, we have generated controlled single-photon pulses, triggered by an external pump pulse. The temporal structure of each photon is determined by the shape of the pump pulse. Single photons were continuously observed at the output port of the cavity for up to 90 minutes. This is an important step towards realizing quantum information processing in a distributed network of trapped ions, interconnected through long-distance photonic channels.

Reduced-Density-Matrix Descriptions for Linear and Non-Linear Coherent Electromagnetic Interactions*
June 8th Dr Verne Jacobs Naval Research Laboratory, Washington, DC

A reduced-density-matrix description is developed for linear and non-linear electromagnetic interactions of quantized electronic systems in the presence of environmental decoherence and relaxation phenomena. Applications of interest include many-electron atomic systems (in electron-ion beam interactions, gases, and high-temperature plasmas) and semiconductor materials (bulk crystals and nanostructures). Time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations are developed in a unified manner. The standard Born (lowest-order perturbation-theory) and Markov (short-memory-time) approximations are systematically introduced within the framework of the general non-perturbative and non-Markovian formulations. A preliminary semiclassical treatment of the electromagnetic interaction is introduced. Compact Liouville-space operator expressions are derived for the linear and the general (nth order) non-linear electromagnetic-response tensors, allowing for coherent initial electronic excitations and for the full tetradic-matrix form of the Liouville-space self-energy operator representing the environmental interactions. It is emphasized that quantum-coherent many-body interactions cannot be adequately treated as environmentally induced phenomena.

*Supported by the Department of Energy, by the Defense Advanced Research Projects Agency, and by the Office of Naval Research

Molecular Astrophysics: A Collisional Approach
June 15th Mr Steven Wrathmall Durham University

With increased accuracy in infrared wavelength observations, the role of atomic and molecular collisions in astrophysics is becoming increasingly important. This talk provides an introduction to the role of atomic and molecular astrophysics within the astrophysical community, the work performed by the group at Durham, and the problems we have been concentrating on, during my first year.

The focus of the talk is on the role of atomic and molecular collisions within the interstellar medium. The theory of rotational excitation for atom-linear molecule and linear molecule-linear molecule systems is presented, and then applied to simple atom-molecular systems using the MOLCOL collisional simulation program. Results for H+SiO and H+CO collisions are discussed, and future work is presented based on our findings.

Soliton Collisions in Atomic Bose-Einstein Condensates
June 29th Mr Andrew Martin Durham University

Soliton collisions in Bose-Einstein condensates of gases of weakly interacting particles are investigated theoretically. Equations of motion for the particle density of a Bose-Einstein condensate are found in the Gross-Pitaevskii equation, and a particular soliton solution is found in the quasi-1D case for condensates of attractively interacting particles. A particle analogy for the solitons is formulated, and Poincare sections derived for two particle collisions. Possible chaotic regimes and the consequences of such chaotic regimes are discussed.

Progress Towards Bose-Einstein Condensation of a Rubidium-Caesium Mixture
July 6th Mr Patrick Tierney Durham University

Soliton collisions in Bose-Einstein condensates of gases of weakly interacting particles are investigated theoretically. Equations of motion for the particle density of a Bose-Einstein condensate are found in the Gross-Pitaevskii equation, and a particular soliton solution is found in the quasi-1D case for condensates of attractively interacting particles. A particle analogy for the solitons is formulated, and Poincare sections derived for two particle collisions. Possible chaotic regimes and the consequences of such chaotic regimes are discussed.

Photodissociation Regions
July 13th Ms Meltem Akyilmaz Durham University