Creation and observation of coherently rotating/vibrating molecular ensembles

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.

Игорь Сергеевич Осадько

Luciano Fonda, N. Mankoč-Borštnik, Mitja Rosina

M. Bitter, E. A. Shapiro, Valery Milner

We report an experimental and theoretical study of the evolution of vibrational coherence in a thermal ensemble of nitrogen molecules. Rotational dephasing and rephasing of the vibrational coherence is detected by coherent anti-Stokes Raman scattering. The existence of rovibrational coupling and the discrete energy spectrum of the rotational bath lead to a whole new class of full and fractional rovibrational revivals. Following the rich rovibrational dynamics on a nanosecond time scale with subpicosecond time resolution enables us to determine the second-order rovibrational constant ${\ensuremath{\gamma}}_{e}$ and assess new possibilities of controlling decoherence.

Andrea Burzo, A. V. Chugreev, Alexei V. Sokolov

We report an experimental observation of simultaneous rotational and vibrational collinear Raman generation in low pressure cooled deuterium gas, with only two narrow-band laser pulses applied at the input of the molecular cell. Only the fundamental vibrational transition ${Q}_{1}$ (0) is driven strongly in this experiment. However, in addition to efficient vibrational Raman generation we observe generation of a large number of rotational sidebands (more than 100) corresponding to ${S}_{0}$ (0) transition. We notice that fine-tuning of the frequency difference of the driving fields near the vibrational Raman resonance changes dramatically the aspects of the generated spectrum and the efficiency of rotational generation: from complete suppression of a self-starting stimulated rotational Raman generation to a strong enhancement of two orders of magnitude. We conduct a numerical analysis that allows us to attribute this behavior to quantum interference among the probability amplitudes of the three molecular states involved.

E. Garmire, F. Pandarese, Charles Hard Townes