Ultrafast dynamics of the coherences in a quantum Hall system

Keshav M. Dani (1, 2) , Jérôme Tignon (3) , Michael Breit (1) , Daniel S. Chemla (1, 2) , Eleftheria Kavousanaki (4) , Ilias E. Perakis (4)

1 LBNL - Lawrence Berkeley National Laboratory [Berkeley]
2 Department of Physics [Berkeley]
3 LPA - Laboratoire Pierre Aigrain
4 Institute of Electronic Structure and Laser

Using three-pulse four-wave-mixing optical spectroscopy, we study the ultrafast dynamics of the quantum Hall system. We observe striking differences as compared to an undoped system, where the 2D electron gas is absent. In particular, we observe a large off-resonant signal with strong oscillations. Using a microscopic theory, we show that these are due to many-particle coherences created by interactions between photoexcited carriers and collective excitations of the 2D electron gas. We extract quantitative information about the dephasing and interference of these coherences.

Domaines: Autre [cond-mat.other]

Keshav M. Dani, Jérôme Tignon, Michael Breit, Daniel S. Chemla, Eleftheria Kavousanaki, et al.. Ultrafast dynamics of the coherences in a quantum Hall system. Physical Review Letters, 2006, 97, pp.057401. ⟨hal-00110001⟩