Decoherence suppression of excitons in GaSe using three successive femtosecond optical pulses

We report the first decoherence control of excitons which was performed on the model semiconductor GaSe by using successive three femtosecond pulses, i.e., the six-wave mixing configuration. The second pulse acts as a π pulse which reverses the time evolution of non-Markovian dynamics. By changing the pulse interval conditions, we confirmed the suppression of exciton decoherence by π pulse irradiation. From the analysis of the decoherence, it is also found that the six-wave mixing technique can successfully be applied to determine the reservoir parameters.