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Q: Fachverband Quantenoptik und Photonik
Q 6: Ultrakalte Moleküle (mit MO)
Q 6.1: Talk
Monday, March 2, 2009, 10:45–11:00, VMP 8 HS
Two-photon coherent control of femtosecond photoassociation — •Mamadou Ndong1, Ronnie Kosloff2, and Christiane P. Koch1 — 1Freie Universität Berlin, Institut für Theoretische Physik, Arnimallee 14, 14195 Berlin — 2Hebrew University, Dept. of Physical Chemistry, Jerusalem 91904, Israel
Photoassociation with short laser pulses has been proposed as a technique to create ultracold ground state molecules. A broad-band excitation seems the natural choice to drive the series of excitation and deexcitation steps required to form a molecule in its vibronic ground state from two scattering atoms. However, one of the main obstacles with broad-band excitations is to eliminate the atomic excitation which hampered first attempts at femtosecond photoassociation. To overcome the ostensible conflict of driving a narrow transition by a broad-band laser, we propose a two-photon photoassociation scheme. When the excitation is carried out by more than one photon, different pathways in the field can be interfered constructively or destructively. Using the idea of rational phase shaping in two-photon transitions, we derive analytical solutions to suppress atomic transitions in both the weak-field and strong-field regime. Two-photon excitation may thus pave the way toward coherent control of photoassociation. We explore the possibility of two-photon femtosecond photoassociation for alkali and alkaline-earth metal dimers and present a detailed study for the example of calcium.