[vip-all] AMO seminar today
Speaker: Uffe V. Poulsen (IFA) Title: Interaction of light with small atomic ensembles Time: Today, 15.15 Place: Fysisk Auditorium Abstract: Collective effects can significantly enhance the emission and absorption of light by an ensemble of two-level atoms. A well-known example is the so-called Dicke super-radiance occurring where excited atoms spontaneously emit light with an intensity scaling as the square of the number of atoms and a peaked angular distribution. In our work, we focus instead on a regime where only a single excitation is stored collectively in the atoms. We study numerically the emission of such an excitation as a photon. It turns out that under suitable conditions, this photon may also be emitted with a peaked angular distribution and we calculate the exact spatio-temporal mode function for various arrangements of the atoms. The phenomenon suggests realistic protocols for storing and retrieving a single photon from an atomic ensemble even without the use of a cavity, a task that is highly relevant for quantum information processing. Peter Staanum and Nicolai Nygaard
Dear All, just to remind you of the extra seminar on Monday 4th May at 10:15 by Tom Baer, a very distingusihed chemical physicist from the US. "Photoelectron photoion coincidence studies with electron velocity focusing. The road to ± 0.1 kJ/mol thermochemistry" This will be a great opportunity to hear about coincidence techniques from a a world expert. I am sure that some of you would be interested in talking with Tom Baer. He will be here the rest of Monday and on Tuesday. If people would like to talk to him, then please be in touch and we can arrange it on Monday. mvh David ABSTRACT: Tomas Baer Chemistry Department, University of North Carolina, USA Photoelectron photoion coincidence studies with electron velocity focusing. The road to ± 0.1 kJ/mol thermochemistry Time: May 4, 10.15 to 11.00 Place: Fysisk Auditorium Threshold photoelectron photoion coincidence (TPEPICO) is used to energy select reactant ions in order to study the dissociation dynamics (rates, branching ratios to various products, product energy distributions) of polyatomic ions. Analysis of the ion time of flight distributions and breakdown diagrams using the statistical theory of unimolecular dissociation permits modeling multiple parallel and sequential dissociation steps, and thus permits extracting quantitative onset energies for higher energy dissociation channels. A recent implementation of this experiment at the Swiss Light Source (SLS) has improved the electron resolution to ± 1 meV, which will lead to 0.1 kJ/mol thermochemistry. Among the molecules investigated at the SLS are the sequential dissociation of MCl4+ to M+ + 4Cl, (M = Sn and Ge). The heat of formation of the neutral MCl4 can be determined by using the final products as an energy anchor. Peter Staanum and Nicolai Nygaard Coffee, tea and cake will be served at 15.05 (a bit late, but never mind). David Field Tel. +45 8942 3650 Fax. +45 8612 0740
participants (2)
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David Field -
Nicolai Nygaard