Berlin 2001 – scientific programme

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AMPD: EPS AMPD

AMPD 7: Sitzung 7

AMPD 7.4: Talk

Thursday, April 5, 2001, 11:55–12:20, H105

Coherent control of bound and free electron wavepackets — •B. Girard, S. Zamith, J. Degert, V. Blanchet, M. A. B. Bouchene, and B. de Beauvoir — LCAR – IRSAMC, Université Paul Sabatier, 118 Rte de Narbonne, 31062 Toulouse Cedex, France

Coherent control has been recently introduced as a new concept to control the dynamics of a quantum system [1,2]. Many variants have been developed in the past years. We present several examples which have been studied (or are still under study) in our group in Toulouse [3–5]. Finally, we will detail some possible applications. Quantum interferences have been widely used in Coherent Control schemes. In our cases, two identical wavepackets are created in a quantum system (atom, molecule) by two identical, time–delayed, laser pulses. The interferences allow to control the excited state wave packet and to monitor its evolution. Various cases are have been explored: one or two photon transitions, saturation or low field regime, bound states or free electron wavepackets. In atoms, these wave packets correspond to spin precession. We show how such a wavepacket can be used to create spin polarised electrons. Alternatively, the shape of free electron wavepackets can also be controlled in such schemes. In a last example, we demonstrate that successive π pulses can be used to code quantum information in a predissociating molecule. The quantum information which is stored can then be read from the shape of the interference pattern which arises in the kinetic energy distribution of the fragments.

[1] R. J. Gordon and S. A. Rice, Annu. Rev. Phys. Chem. 48, 601 (1997).

[2] M. Shapiro and P. Brumer, Int. Rev. Phys. Chem. 13, 187 (1994).

[3] V. Blanchet, C. Nicole, M. A. Bouchene and B. Girard, Phys. Rev. Lett. 78, 2716 (1997).

[4] V. Blanchet, M. A. Bouchene and B. Girard, J. Chem. Phys. 108, 4862 (1998).

[5] B. Girard, M. A. Bouchene, V. Blanchet, C. Nicole and S. Zamith, Ultrashort Wave Packet Dynamics and Interferences in Alkali Atoms, in Atomic and Molecular Beams. The State of the Art 2000, edited by R. Campargue (Springer–Verlag, 2000), pp. 145.