Femtosecond spectral electric field reconstruction using coherent transients

We have implemented a new approach for measuring the time-dependent intensity and phase of ultrashort optical pulses. It is based on the interaction between shaped pulses and atoms, leading to coherent transients.Comment: 4 pages Accepted in Optics Letter

A pump-probe study of the formation of rubidium molecules by ultrafast photoassociation of ultracold atoms

An experimental pump-probe study of the photoassociative creation of translationally ultracold rubidium molecules is presented together with numerical simulations of the process. The formation of loosely bound excited-state dimers is observed as a first step towards a fully coherent pump-dump approach to the stabilization of Rb$_2$ into its lowest ground vibrational states. The population that contributes to the pump-probe process is characterized and found to be distinct from a background population of pre-associated molecules.Comment: Accepted for publication in Phys. Rev. A (10 pages, 9 figures

Factorization of Numbers with the temporal Talbot effect: Optical implementation by a sequence of shaped ultrashort pulses

We report on the successful operation of an analogue computer designed to factor numbers. Our device relies solely on the interference of classical light and brings together the field of ultrashort laser pulses with number theory. Indeed, the frequency component of the electric field corresponding to a sequence of appropriately shaped femtosecond pulses is determined by a Gauss sum which allows us to find the factors of a number

Time-dependent photoionization of azulene: Optically induced anisotropy on the femtosecond scale

We measure the photoionization cross-section of vibrationally excited levels in the S2 state of azulene by femtosecond pump-probe spectroscopy. At the wavelengths studied (349-265 nm in the pump) the transient signals exhibit two distinct and well-defined behaviours: (i) Short-term (on the order of a picosecond) polarization dependent transients and (ii) longer (10 ps - 1 ns) time-scale decays. This letter focuses on the short time transient. In contrast to an earlier study by Diau et al.22 [J. Chem. Phys. 110 (1999) 9785.] we unambiguously assign the fast initial decay signal to rotational dephasing of the initial alignment created by the pump transition.Comment: Chemical Physics Letters (2008

Space-time coupling of shaped ultrafast ultraviolet pulses from an acousto-optic programmable dispersive filter

A comprehensive experimental analysis of spatio-temporal coupling effects inherent to the acousto-optic programmable dispersive filter (AOPDF) is presented. Phase and amplitude measurements of the AOPDF transfer function are performed using spatially and spectrally resolved interferometry. Spatio-temporal and spatio-spectral coupling effects are presented for a range of shaped pulses that are commonly used in quantum control experiments. These effects are shown to be attributable to a single mechanism: a group-delay--dependent displacement of the shaped pulse. The physical mechanism is explained and excellent quantitative agreement between the measured and calculated coupling speed is obtained. The implications for quantum control experiments are discussed.Comment: 8 pages, 6 figures; accepted for publication within JOSA

Real time Quantum state holography using coherent transients

In a two level atom, real-time quantum state holography is performed through interferences between quantum states created by a reference pulse and a chirped pulse resulting in coherent transients. A sequence of several measurements allows one to measure the real and imaginary parts of the excited state wave function. These measurements are performed during the interaction with the ultrashort laser pulse. The extreme sensitivity of this method to the pulse shape provides a tool for electric field measurement

Façonnage d'impulsions femtosecondes dans l'ultraviolet, factorisation de grands nombres, contrôle cohérent de systèmes atomiques et moléculaires

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF