Floquet-Engineered Valleytronics in Dirac Systems

TL;DR

This paper explores how intense light can be used to control valley degrees of freedom in Dirac materials, enabling optically tunable valley currents and valley valves for quantum information applications.

Contribution

It introduces a novel optical method to manipulate valley polarization in Dirac systems using Floquet engineering, applicable to graphene and similar materials.

Findings

Demonstrates robust valley polarization under optical Floquet control

Proposes a concrete optical valley valve device

Shows resilience against disorder and parameter variations

Abstract

Valley degrees of freedom offer a potential resource for quantum information processing if they can be effectively controlled. We discuss an optical approach to this problem in which intense light breaks electronic symmetries of a two-dimensional Dirac material. The resulting quasienergy structures may then differ for different valleys, so that the Floquet physics of the system can be exploited to produce highly polarized valley currents. This physics can be utilized to realize a valley valve whose behavior is determined optically. We propose a concrete way to achieve such valleytronics in graphene as well as in a simple model of an inversion-symmetry broken Dirac material. We study the effect numerically and demonstrate its robustness against moderate disorder and small deviations in optical parameters.