Abstract-Ultrafast terahertz nonlinear optics of Landau level transitions in a monolayer graphene

Go Yumoto, Ryusuke Matsunaga, Hiroki Hibino, and Ryo Shimano

https://journals.aps.org/prl/accepted/85071Yb3X8a14b5b084a77887f1fd7112a6574506


We investigated the ultrafast terahertz (THz) nonlinearity in a monolayer graphene under the strong magnetic field using THz pump-THz probe spectroscopy. An ultrafast suppression of the Faraday rotation associated with inter-Landau level (LL) transitions is observed, reflecting the Dirac electron character of non-equidistant LLs with large transition dipole moments. A drastic modulation of electron distribution in LLs is induced by far off-resonant THz pulse excitation in the transparent region. Numerical simulation based on the density matrix formalism without rotating wave approximation reproduces the experimental results, indicating that the strong light-matter coupling regime where the Rabi frequency exceeds the carrier wave frequency and even the relevant energy scale of the inter-LLs transition is realized.