Behavior of Floquet Topological Quantum States in Optically Driven Semiconductors

Abstract

Spatially uniform optical excitations can induce Floquet topological band structures within insulators which can develop similar or equal characteristics as are known from three-dimensional topological insulators. We derive in this article theoretically the development of Floquet topological quantum states for electromagnetically driven semiconductor bulk matter and we present results for the lifetime of these states and their occupation in the non-equilibrium. The direct physical impact of the mathematical precision of the Floquet-Keldysh theory is evident when we solve the driven system of a generalized Hubbard model with our framework of dynamical mean field theory (DMFT) in the non-equilibrium for a case of ZnO. The physical consequences of the topological non-equilibrium effects in our results for correlated systems are explained with their impact on optoelectronic applications.

Self-consistent quantum field theory for the characterization of complex random media by short laser pulses

“…The current j ω ( r ) may be expanded in orders of ω [97,98]. We do not take into account here a coupling to a microscopic model for dynamical feedback of the optically driven crystal in the non-equilibrium [99][100][101], or to chaos modulations and chaotic systems [102]. The dielectric constant is spatially dependent, ( r ) = b + ∆ V ( r ), and the dielectric contrast is defined as ∆ = scat − b .…”

Quantum Many-Body Theory for Exciton-Polaritons in Semiconductor Mie Resonators in the Non-Equilibrium

“…[34]. By checking the Floquet sum we find that considering the first ten (n = 10) Floquet modes is sufficient within the numerical accuracy of the DMFT [14,15]. A cut-off after a smaller number would lead to a drift in the total energy of the system and thus it would hurt conservation laws.…”

“…These peaks give evidence that such a sample may undergo a transition towards exciton-polariton lasing rather than a transition to exciton-photon lasing, at least a coexistence of both regimes may occur. ZnO is known for excellent light-matter coupling characteristics [7,[14][15][16][17][18][19][20][21][22][23][24][25][26][27]; it is predestined for this study. It has been experimentally derived that ZnO can be considered as a Mott insulator under certain conditions [16,18].…”

“…It leads to quantum many body physics and the renormalization of the bands under excitations. We consider (i) the semiconductor material as it is subjected to the strong external AC field of the optical pump in the sense of a topological excitation [14,15]. We model the coupling of the classical laser,hΩ L = 1.75 eV, to the quantum many body system as well as higher-order photon absorption processes,hΩ L = 3.5 eV etc., by means of the Floquet matrix [28][29][30][31].…”

“…The rocksalt configuration is distinguished by a tunable gap from 1.8 eV up to 6.1 eV, a gap value of 3.38 eV is typical for the monocrystal rocksalt configuration without oxygen vacancies [23,24]. As such the rocksalt configuration could be suited for higher harmonics generation under non-equilibrium topological excitation [14,15,36]; (c) Typical setup of a solid state random laser: Densely packed disordered ZnO nano-resonators are embedded in a waveguide. The sample is externally pumped in (111) direction.…”