AtMol Research Seminar Archive
Index Current Seminars

Epiphany Term 2007

Date Speaker Home
Quantum computing with macroscopic fluorescence signals
January 17th Dr Almut Beige University of Leeds

Finding a quantum computing architecture that is scalable and robust against dissipation remains a challenge for both, experimentalists and theoreticians. Over the last years, several strategies to overcome the decoherence problems have been proposed. Here we describe a scheme for the preparation of cluster states for one-way quantum computing. It is shown that the generation of atom entanglement in atom-cavity systems requires neither the coherent evolution of product states nor the detection of single photons [1]. Instead the preparation of the desired state is heralded by the observation of a macroscopic fluorescence signal.

[1] J Metz, M Trupke, and A Beige, Phys Rev Lett 97, 040506 (2006).

The Abraham-Minkowski Controversy and Atom Optics.
January 24th Mr Mark Bason Atomic and Molecular Physics

The momentum of a photon in a dispersive medium has been debated for nearly a century. Abraham and Minkowski had different formulations to this problem, each emerging from fundamental physics. I will be looking at how Ketterle's group at MIT approached this problem using BEC and atom interferometry.
Reference: PRL 94, 170403 (2005)

January 31st No seminar No seminar

Due to British Airways industrial action, Dr Koch's seminar was postponed for one week.

Ultracold & ultrafast: Making and manipulating ultracold molecules with time-dependent laser fields
February 7th Dr Christiane Koch Freie Universität Berlin

While ultracold matter brought quantum effects onto the macroscopic scale, ultrafast lasers made quantum dynamical phenomena observable in real-time. Bringing the two together seems natural and holds the promise of employing quantum interferences in an unprecedented way. Photoassociation provides an optimal framework for the merger since it relies in principle only on the presence of optical transitions which generally are abundant. Combining it with coherent control where the potential energy surfaces governing the dynamics can be 'shaped', a general route toward stable ultracold molecules is obtained. This seems promising in the quest for a molecular Bose-Einstein condensate in its internal ground state. I will present theoretical predictions for coherent photoassociation, compare to the current status of experiments and discuss future perspectives of manipulating ultracold matter with ultrafast lasers.

Venue: Appleby Lecture Theatre; W103; Geography department.

Creating cold slow molecules with intense optical fields
February 14th Dr Peter Barker University College London

Although some ultra-cold molecular species can now be produced on Feshbach resonances and by photoassociation of laser cooled atomic species, there is considerable interest in developing general techniques to produce cold molecules of species that cannot be created by association of laser cooled atoms.

Our work in this rapidly developing field has centered on the development of optical Stark deceleration which allows the creation of cold stationary molecules from a cold molecular beam using intense far detuned optical fields. This scheme is general because it relies on the polarizability interaction and since all molecules are polarizable, in principle any molecule or atom can be manipulated and slowed in the same way. In this talk I will describe our recent experiments where we have used pulsed optical lattices to decelerate and accelerate cold molecules in a molecular beam and also discuss future work to trap and further cool these molecules.

Coherent Manipulations of Atomic Qubits in Moving Tweezers.
February 21st Dr Antoine Browaeys Orsay
Touchdown on Titan
February 28th Prof. John Zarnecki Open University

Prof. Zarnecki is the Director of the Open University's Planetary & Space Sciences Research Institute and he led the team that provided one of the instruments on the European Space Agency's Huygens Probe. In 2005 Huygens landed on the surface of Titan, the largest of Saturn's moons, after a 7 year interplanetary journey. Titan, which is larger than the planet Mercury, is the only planetary satellite in the entire Solar System to possess a significant atmosphere. This atmosphere is the site of a range of chemical reactions which produce complex hydrocarbon molecules similar to the processes which are likely to have occurred in Earth's early atmosphere over 4 billion years ago. The journey of the Huygens probe will be described as well as its final dramatic plunge to the surface. Results will be presented as well as prospects for future missions.

The 2007 Grubb-Parsons Lecture starts at 4:30pm in the Scarborough Lecture Theatre.

Modern Molecular Quantum Theory: Mini-symposium
March 7th Prof Trygve Helgaker
Prof Mark Child

2.40 pm Welcome (CG60; Chemistry department)

2.45 pm Prof. Trygve Helgaker (Oslo)
"The right result for the right reason: a tour of high-accuracy quantum-chemical methods"

3.45 pm Tea

4.15 pm Prof. Mark S. Child (Oxford)
Royal Society of Chemistry Boys-Rahman Lecture
"Coupled coherent state simulation of multidimensional systems"

5.20 pm "Meet the speakers" reception, Musgrave Room (CG141)

The KAM theorem and its applications.
March 14th Mark Saunders Atomic and Molecular Physics

The role of chaotic resonances in the Solar System explain gaps observed in the asteroid belt and the irregular trajectories of planets.
Systems from atomic physics and astronomy explained by the KAM theorem are presented.

KAM theorem:
[1] A.N. Kolmogorov; On conservation of conditionally periodic motions under small perturbations of the Hamiltonian; Dokl. Akad. Nauk 98 527 (1953)
[2] V.I. Arnol'd; Proof of A.N. Kolmogorov's theorem on the preservation of quasi-periodic motions under small perturbations of the Hamiltonian;
Uspethi Mat. Nauk. 18 13 (1960); Russian Math. Surv. 18 9 (1960 - English).
[3] J. Moser; On invariant curves of area-preserving mappings of an annulus; Nachr. Akad. Wiss. Gottingen Math. Phys. K 1 87 (1962)

Astronomy examples:
[4] N. Murray & M. Holman; The role of chaotic resonances in the Solar System; Nature; 410 775 (2001)
[5] S.F. Dermott & C.D. Murray; Nature of the Kirkwood gaps in the asteroid belt; Nature; 301 201 (1983)
[6] F. Namouni, A.A. Christou, & C.D. Murray; Coorbital Dynamics at Large Eccentricity and Inclination; Phys. Rev. Lett. 83 2506 (1999)

Atomic physics applications:
[7] T. Kinoshita, T. Wenger, & D.S. Weiss; A quantum Newton's cradle; Nature; 440 900 (2006)
[8] A. Buchleitner, M. B. d'Arcy, S. Fishman, S.A. Gardiner, I. Guarneri, Z.-Y. Ma, L. Rebuzzini,& G.S. Summy;
Quantum Accelerator Modes from the Farey Tree; Phys. Rev. Lett. 96 164101 (2006)

[9] T.M. Fromhold et. al.; Chaotic electron diffusion through stochastic webs enhances current flow in superlattices; Nature; 428 726 (2004)

Young Atom Opticians Conference
March 27th to 31st YAO2007 Durham University