Atomic & Molecular Spectroscopy by Saturation with Coherent Light

Theodor W. Hänsch

Hui Chen

This work is devoted to the study of the quantum coherent effects in diatomic molecular systems by using high resolution laser spectroscopy. In particular, we have studied\nthe rubidium diatomic molecular gaseous medium's absorption spectrum with high\nresolution single mode laser spectroscopy. The derived electronic and rotational vibrational constants were used in the backward Raman amplification experiment of\nRb diatomic molecule. Both experimental results and theoretical calculation confirms that there is strong backward directionally dependent radiation. This effect can\nfurther be utilized in remote detection of chemical material.\nIn the saturated spectroscopy experiment of the cesium diatomic molecule, long-lived ground state coherence was observed. The coherence would decay at a rate less\nthan the natural life time of the excited states, which indicates great possibility for\nperforming the quantum optics experiments previously performed in atomic systems\nonly.\nElectromagnetically induced transparency has been observed in many atomic\nsystems for many years, while it has been seldom realized in molecular systems.\nIn our experiment of electromagnetically induced transparency in cesium diatomic\nmolecules, we utilized  energy levels, and observed subnatural linewidth. This is the first time to realize a  type EIT in a molecular ensemble. This experiment will\nlead to many other experiments of quantum effects in a molecular system, such like\nmagnetic optical rotation, light storage in ensemble of molecules.\nMagnetically induced chirality in an atomic ensemble is also investigated in my\nresearch.

Fetah Benabid, P. S. Light, F. Couny

We review the results of the work done on coherent effects in hollow-core photonic crystal fibers. These include generation of electromagnetically induced transparency and saturable absorption spectroscopy in molecular gases and atomic vapours.

W.R.S. Carton

E. Gaižauskas, Gediminas Trinkūnas

An overview of the influence of coherent coupling in light–matter interaction traced by transients in pumpprobe spectroscopy is given, with special emphasis on interest and works provided by the authors. Advantages of this technique used to trace pathways of transfer and decay of quantum coherences in atoms, molecular aggregates, and biological structures, as well as feasibility of the probing of both the lifetime and characteristic lengths (area, volume) of coherent excitations are discussed. Theoretical analysis of the pump-probe measurements is based on the numerical solution of the equation for the reduced density matrix in the representation of atomic, molecular, and excitonic states, considering coherent coupling between light and appropriate quantum states precisely.

Theodor W. Hänsch, I. S. Shahin, ARTHUR L. SCHAWLOW