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Acta Sinica Quantum Optica

Coherent Population Transfer in a Four-Level Quasi-Lambda System Driven by Unmatched Gaussian Pulses

Xiangwei Wang

Published Jan 1, 2010• 0 citations
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Abstract

The population transfer in a four-level quasi-lambda system driven by unmatched Gaussian pulses is investigated.By using the matrix equation theory,evolutions of the populations of the four states Vs time is investigated.Numerical simulations show that the Rabi frequency intensity and detuning of pumping field have different effects on the population transfer comparing with the probe and coupling field;and spontaneously generated coherence(SGC)have little effect on population transfer.If the parameters are chosen appropriately,population can be transferred almost completely to the target state.

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In this paper we study influences of Doppler broadening,spontaneously generated coherence,and other system parameters on propagation effect in a quasi lambda-type four-level atomic system.It is shown that when the Doppler broadening is present,generally speaking,the values of gain and intensity of lasing without inversion (i.e.the probe field) in the co-propagating probe and driving fields case are much larger than those in the counter-propagating case;considerably larger gain and intensity of lasing without inversion than those without the Doppler broadening can be obtained by choosing appropriate values of the Doppler broadening width and spontaneously generated coherence strength.The gain and intensity of lasing without inversion increase with the increase of spontaneously generated coherence strength;when spontaneously generated coherence is present,much larger gain and intensity of lasing without inversion than those in the case without spontaneously generated coherence can be obtained.Choosing suitable values of the probe detuning,Rabi frequencies of the driving and pump fields at the entrance of the medium also can remarkably enhance the gain and intensity of lasing without inversion.更多还原

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The population transfer in a four-level quasi-lambda system driven by unmatched Gaussian pulses is investigated.By using the matrix equation theory,evolutions of the populations of the four states Vs time is investigated.Numerical simulations show that the Rabi frequency intensity and detuning of pumping field have different effects on the population transfer comparing with the probe and coupling field;and spontaneously generated coherence(SGC)have little effect on population transfer.If the parameters are chosen appropriately,population can be transferred almost completely to the target state.
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In this paper we study influences of Doppler broadening, spontaneously generated coherence, and other system parameters on propagation effect in a quasi lambda-type four-level atomic system. It is shown that when the Doppler broadening is present, generally speaking, the values of gain and intensity of lasing without inversion (i.e. the probe field) in the co-propagating probe and driving fields case are much larger than those in the counter-propagating case; considerably larger gain and intensity of lasing without inversion than those without the Doppler broadening can be obtained by choosing appropriate values of the Doppler broadening width and spontaneously generated coherence strength. The gain and intensity of lasing without inversion increase with the increase of spontaneously generated coherence strength; when spontaneously generated coherence is present, much larger gain and intensity of lasing without inversion than those in the case without spontaneously generated coherence can be obtained. Choosing suitable values of the probe detuning, Rabi frequencies of the driving and pump fields at the entrance of the medium also can remarkably enhance the gain and intensity of lasing without inversion.
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In this paper we study influences of Doppler broadening,spontaneously generated coherence,and other system parameters on propagation effect in a quasi lambda-type four-level atomic system.It is shown that when the Doppler broadening is present,generally speaking,the values of gain and intensity of lasing without inversion (i.e.the probe field) in the co-propagating probe and driving fields case are much larger than those in the counter-propagating case;considerably larger gain and intensity of lasing without inversion than those without the Doppler broadening can be obtained by choosing appropriate values of the Doppler broadening width and spontaneously generated coherence strength.The gain and intensity of lasing without inversion increase with the increase of spontaneously generated coherence strength;when spontaneously generated coherence is present,much larger gain and intensity of lasing without inversion than those in the case without spontaneously generated coherence can be obtained.Choosing suitable values of the probe detuning,Rabi frequencies of the driving and pump fields at the entrance of the medium also can remarkably enhance the gain and intensity of lasing without inversion.更多还原