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Physical Review A

Enhancing photoassociation efficiency by using a picosecond laser pulse with cubic-phase modulation

Wei Zhang, Ting Xie, Yin Hui Huang, Shu‐Lin Cong

Published Dec 27, 2011• 12 citations
Publisher

Abstract

The photoassociation (PA) dynamics of ultracold cesium atoms steered by the picosecond laser pulse with cubic-phase modulation has been investigated theoretically by solving numerically the time-dependent Schr\"odinger equation using the mapped Fourier grid method. The temporal duration of the pulse is prolonged, and the pulse area is enlarged by modulating the cubic phase. The PA efficiency is related to the pulse area. When the pulse area is larger than a certain value, the cubic-phase pulses noticeably enhance the PA efficiency, although they have lower energies.

DOI
10.1103/physreva.84.065406

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The formation of ultracold Cs 2 molecules via photoassociation (PA) with a spectral π-jump laser pulse is theoretically investigated by solving the time-dependent Schrödinger equation using the mapped Fourier grid method. Numerical calculations show that the population distributions of associated molecules mainly result from the off-resonant excitation of the π-jump laser pulse. Compared with the transform-limited pulse, an efficient population accumulation in the PA process is achieved with the π-jump pulse. An oscillation pattern appears in the population on the vibrational levels of the state owing to the action of the post-half-pulse in the π-jump pulse. The PA efficiency is related to the Rabi angle of the laser pulse. A π-jump pulse can be used to enhance more effectively the PA efficiency than a transform-limited pulse with the same Rabi angle.
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The photoassociation dynamics of ultracold lithium atoms controlled by a cut-off pulse has been investigated theoretically by solving numerically the time-dependent Schrodinger equation using the mapped Fourier grid method. The frequency components of the laser pulse close to the atomic resonance are partly cut off. Compared with the typical Gauss-type pulses, the cut-off pulse is helpful to suppress efficiently the weakly bound states and prepare the associated molecules in the lower vibrational states. Especially, the dependence of photoassociation probability on the cut-off position of the laser pulse is explored.
The photoassociation dynamics of ultracold lithium atoms controlled by a cut-off pulse has been investigated theoretically by solving numerically the time-dependent Schro¨dinger equation using the mapped Fourier grid method. The frequency components of the laser pulse close to the atomic resonance are partly cut off. Compared with the typical Gauss-type pulses, the cut-off pulse is helpful to suppress efficiently the weakly bound states and prepare the associated molecules in the lower vibrational states. Especially, the dependence of photoassociation probability on the cut-off position of the laser pulse is explored.
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