Development of the and control of decoherence based on genetic algorithm

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We have so far developed a phase-controlled light source called APM to manipulate quantum phases of matter on the attosecond scale, and have successfully applied APM to the coherent control of isolated molecules in the gas phase with an ultrahigh precision. In order to apply such coherent control to condensed phases, decoherence needs to be controlled. Decoherence is a phenomenon where coherence is lost in the interaction of the system with an environment. It is important not only from a viewpoint of coherent control but also from a fundamental point of view regarding the quantum-classical boundary. It is not yet understood very well how coherence, which is dearly seen in matter on the atomic and molecular scales, becomes difficult to be seen with the system being complex and large. The purpose of the present research is to test and control decoherence by using APM to serve as a sensitive and quantitative detector of decoherence.We have carried out experiments where vibrational wave pa … More ckets generated in the iodine molecules with an ultrashort laser pulse are irradiated with an intense near infrared laser pulse to actively induce decoherence. In these experiments, we have observed that the quantum amplitudes of the wave packets have been decreased with the irradiation of the near infrared laser pulse. Moreover we have applied APM to this system and have observed that quantum phases of the wave packets have been shifted with the infrared pulse. These amplitude-decrease and phase shift have been controlled by tuning the timing of the infrared pulse and by modulating its optical phase. We have thus succeeded in developing a decoherence simulator where intense near infrared laser pulses and APM are combined to be applied to the gas-phase molecules. Apart from this &coherence simulator, we have been developing an apparatus for the experiment where similar decoherence simulator will be applied to the iodine molecules embedded in a solid para-hydrogen prepared in a cryostat. We have not yet employed, however; a feedback control based on genetic algorithm to the phase modulation of the near infrared laser pulse of the decoherence simulator. These efforts will be continued after this project. Less