Long valley lifetime of dark excitons in single-layer WSe₂.

ABSTRACT: Single-layer transition metal dichalcogenides provide a promising material system to explore the electron's valley degree of freedom as a quantum information carrier. The valley degree of freedom can be directly accessed by means of optical excitation. However, rapid valley relaxation of optically excited electron-hole pairs (excitons) through the exchange interaction has been a major roadblock. Theoretically such valley relaxation is suppressed in dark excitons, suggesting a potential route for long valley lifetimes. Here we develop a waveguide-based method to detect time-resolved and energy-resolved dark exciton emission in single-layer WSe₂, which involves spin-forbidden optical transitions with an out-of-plane dipole moment. The valley degree of freedom of dark excitons is a

SUBMITTER: Tang Y 

PROVIDER: S-EPMC6731252 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature