Elucidation and coherent control of excitonic states of carbon nanotubes

本研究旨在阐明单壁碳纳米管（SWNTs）的激子态，并发展基于激子态的相干控制技术。为此，(1)我们建立了产生振幅超过1MV/cm电场的单周期太赫兹脉冲的方法。(2)建立了太赫兹非线性光谱方法，观察了ZnSe和GaAs量子阱在强太赫兹脉冲下的激子电离与Stark效应和动态Frantz-Keldysh效应。此外，(3)我们首次证明，在太赫兹脉冲的照射下，GaAs量子阱的载流子数量增加了103倍，最终导致明亮的近红外发光。(4)为了研究单壁碳纳米管的太赫兹响应，我们研制了太赫兹近场显微镜。利用发展起来的太赫兹光谱技术，我们继续进行太赫兹相干控制激子态的实验。

Aim of this study is to elucidate excitonic states of single-walled carbon nanotubes (SWNTs) and to develop coherent control technique with the excitonic states. For this purpose, (1) we established the method to generate single-cycle THz pulses with amplitudes with exceeding 1MV/cm electric field. (2) By developing a THz nonlinear spectroscopic method, we observe excitonic ionization under strong THz pulse with Stark effect and dynamical Frantz-Keldysh effect for both ZnSe and GaAs quantum wells. Furthermore, (3) we demonstrated for the first time that the number of carriers of GaAs quantum wells is enhanced 103 times more by irradiation of the THz pulse, eventually which leading a bright near-infrared luminescence. (4) For study THz response of single SWNTs, we developed the THz near-field microscope. With the developed THz spectroscopic technique we continue the experiment for the THz coherent control of excitonic states.