August 9, 1999
Future directions in research:
Laser manipulation of atoms and molecules is of both fundamental and practical significance. All-optical alignment and orientation provide fundamentally new and elegant ways of controlling nonpolar molecular species that cannot be aligned or oriented by brute force external magnetic or electric fields. We have recently demonstrated how the |MJ|- dependent molecular Autler - Townes splitting can be used to prepare aligned populations of nonpolar molecules (J. Qi, G. Lazarov, X. Wang, L. Li, L. Narducci, A. M. Lyyra and F. C. Spano," Autler-Townes Splitting in Molecular Lithium: Prospects for All-Optical Alignment of Nonpolar Molecules", Phys. Rev. Letters 83, 288-291 (1999)). We are exploring as an extension of our work to include an all-optical technique for molecular orientation. In addition, we propose a novel use of the Autler-Townes effect to create controllable linear combinations of molecular wavefunctions in the dressed state basis, leading to a new method for quantum state control.
Our plan is to:
A. Complete the development of the technique of all-optical alignment and orientation of nonpolar molecules based on Autler-Townes MJ -dependent energy splittings. This involves utilizing the high resolution available from a well collimated molecular beam with the Autler-Townes MJ - dependent energy splittings achievable with cw laser fields. We also plan to complete laser polarization related aspects of our work, i.e. moving from molecular alignment (linear polarization) to molecular orientation (circular polarization).
B. Enhance the Autler-Townes MJ - dependent energy splittings and hence the degree of alignment or orientation by using pulse amplification of the cw laser. This greatly increases the utility of this technique for different applications.
C. Apply this technique in quantum state control. Specifically, we plan to use this technique to modify the character (singlet vs. triplet) of a (dressed) molecular wavefunction. Such a light-induced gateway state can be used to enhance triplet state production, a step that could lead to the ability to make direct comparisons of reactivities of singlet vs. triplet states.
D. Continue our theoretical studies of coherence effects as well as nonlinear optical properties of our multilevel system. The ultimate goal is to attain total population transfer to a selected magnetic substate in the spirit of the Stimulated Raman Adiabatic Passage technique.
E. Utilize our high resolution cw triple resonance capability and the
molecular beam system to continue our shape resonance studies of alkali
molecules. We have recently identified a 7Li2 shape
resonance. We plan to extend this work to heavier mixed alkalis.
Our goal is not only to provide high resolution shape resonance data but
also the needed bridge of the vibrational assignment from bound state spectroscopy
to photoassociative spectroscopy, where this information is not available.
Both of these are critical pieces of information for accurate determination
of scattering lengths, a critical parameter for Bose-Einstein condensation
studies.