Berry phases of quantum trajectories in semiconductors under strong terahertz fields

Abstract

Quantum evolution of particles under strong fields can be essentially captured by a small number of quantum trajectories that satisfy the stationary phase condition in the Dirac-Feynmann path integrals. The quantum trajectories are the key concept to understand extreme nonlinear optical phenomena, such as high-order harmonic generation (HHG), above-threshold ionization (ATI), and high-order terahertz sideband generation (HSG). While HHG and ATI have been mostly studied in atoms and molecules, the HSG in semiconductors can have interesting effects due to possible nontrivial "vacuum" states of band materials. We find that in a semiconductor with non-vanishing Berry curvature in its energy bands, the cyclic quantum trajectories of an electron-hole pair under a strong terahertz field can accumulate Berry phases. Taking monolayer MoS${}_2$ as a model system, we show that the Berry phases appear as the Faraday rotation angles of the pulse emission from the material under short-pulse excitation. This finding reveals an interesting transport effect in the extreme nonlinear optics regime.

5 pages

References in corpus (8)

• The electronic properties of graphene
• Control of valley polarization in monolayer MoS2 by optical helicity
• Valley polarization in MoS2 monolayers by optical pumping
• Electrical Control of Two-Dimensional Neutral and Charged Excitons in a Monolayer Semiconductor
• Optical Generation of Excitonic Valley Coherence in Monolayer WSe2
• Monolayer MoS2: trigonal warping, "Γ-valley", and spin-orbit coupling effects
• Second-order nonlinear optical effects of spin currents
• Direct measurement of a pure spin current by a polarized light beam

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• Nonlinear optical response induced by non-Abelian Berry curvature in time-reversal-invariant insulators
• Detection of the anomalous velocity with sub-picosecond time resolution in semiconductor nanostructures
• Probing dephasing time of crystals via spectral properties of high-harmonic generation
• Dynamics of the effective mass and the anomalous velocity in two-dimensional lattices
• An explicit formula for high-order sideband polarization by extreme tailoring of Feynman path integrals
• Ultrafast pseudomagnetic fields from electron-nuclear quantum geometry
• Unoccupied Topological Surface State in MnBi${}_2$Te${}_4$