HiSORセミナー
シンクロトロン放射によるヘリウム原子のアト秒コヒーレント制御
日時 2020年3月24日 （火） 13：30-14：15(頃)
場所 放射光科学研究センター 2階 セミナー室
講師 金安達夫
(九州シンクロトロン光研究センター)
Quantum manipulation of populations and pathways in matter by light pulses, so-called coherent control, is currently one of the hottest research areas in optical physics and photochemistry. In the last two decades, coherent control of a quantum system has been extensively studied using optical lasers which provide phase-locked sequential pulses. Moreover recent advent of the high harmonic laser source and seeded free electron lasers (FELs) has enabled the coherent control at extreme ultraviolet (XUV) regions. Recently we demonstrated an unremarked capability of synchrotron radiation on the coherent control [1,2]. Our method is based on the potential use of undulator radiation as longitudinally coherent wave packets, which has been hidden in the incoherent nature of the radiation pulse.
The experiments were carried out at the 750-MeV UVSOR-III storage ring. We used the pairs of 10-cycle radiation wave packets with attosecond-controlled spacing emitted from the tandem undulator consisted of twin APPLE-II type devices. Based on the wave packet interferometry scheme, we succeeded in the attosecond control of the population [1] and orbital alignment [2] in photoexcitation of helium atoms in the extreme ultraviolet (XUV) region by tuning the time delay of the double pulse structure in each wave packet. Since our technique uses a synchrotron light source, it is extendable as far as hard x-ray. This new capability of synchrotron light sources will open up the possibilities of probing and controlling ultrafast phenomena in a broad range of physics research.
FIGURE 1. (a) Experimental setup for the coherent control of atoms using synchrotron radiation. (b) Population control in photoexcitation of helium atom.
[1] Y. Hikosaka et al., Nature Communications 10, 4988 (2019) .
[2] T. Kaneyasu et al., Phys. Rev. Lett. 123, 233401 (2019).
問合せ先 加藤政博（放射光科学研究センター）
