SAMOP 2023 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 25: Solid State Quantum Optics

Q 25.8: Talk

Wednesday, March 8, 2023, 12:45–13:00, E001

Valley polarization in pristine graphene with linearly polarised laser pulses — •Arkajyoti Maity, Ulf Saalmann, and Jan M. Rost — Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38,01187 Dresden

Information processing using preferential excitation of one of the two energy degenerate valleys in inversion symmetry broken graphene-like systems has been achieved by circularly polarized pulses. These pulses couple differentially to the valleys which have opposite orbital angular momentum, depending on their polarization[1]. Recent studies have, however, shown that linearly polarised light pulses can generate appreciable valley polarization, even in pristine graphene, without breaking inversion symmetry at the Hamiltonian level[2]. In our presentation, we will shed some light on the general mechanisms of this process of valley polarization with ultrashort laser pulses. We also show results for the terahertz regime, in which graphene shows strong non-linear behavior, and discuss the role of electronic decoherences for such longer pulses.

[1]Di Xiao, Wang Yao, and Qian Niu. Valley-contrasting physics in graphene:Magnetic moment and topological transport. Phys. Rev. Lett., 99:236809,Dec 2007 [2]Hamed Koochaki Kelardeh, Ulf Saalmann, and Jan M. Rost. Ultrashortlaser-driven dynamics of massless dirac electrons generating valley polarization in graphene. Phys.Rev.Research, 4:L022014, Apr 2022