Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 5: Posters Tuesday (Photoionisation, Multi Photon Processes)
A 5.34: Poster
Dienstag, 3. April 2001, 12:30–15:00, AT3
Quantum interference in the third-harmonic generated by two time-delayed coherent laser pulses. — •Lorenzo Fini1, Stefano Cavalieri1, and Roberto Buffa2 — 1INFM, Dipartimento di Fisica and LENS, Università di Firenze, Largo E. Fermi 2, 50125, Firenze, Italy. — 2INFM and Dipartimento di Fisica, Università di Siena, Via Banchi di Sotto 55, 53100 Siena, Italy
In a recent experiment on three-photon ionisation of atomic barium,performed with a sequence of two coherent nanosecond laser pulses,we demonstrated that the quantum-interference properties of the ionisation process can be investigated on a time-scale much shorter than the duration of the laser pulses. In the present work we extend our investigation to the quantum coherence properties of the third-harmonic generation process in an atomic vapour. We utilise an interferometric technique involving two delayed pulses of a multi-mode, nanosecond dye laser to investigate the resonance-enhanced third-harmonic generation in sodium vapour. The fringe pattern that is observed in the third-harmonic emission as a function of the time delay of the two pulses carries the information on the quantum coherence properties of the atomic polarisation. This kind of process opens new interesting possibilities in the field of time-delay spectroscopy.