Quantum valley pseudospin controlled by strain

TL;DR

This paper proposes using uniaxial strain to manipulate valley pseudospin in 2D materials, enabling ultrafast control of quantum information encoded in valley states with potential applications in quantum technologies.

Contribution

It introduces a novel strain-based method for controlling valley pseudospin, offering a more flexible and robust alternative to external field manipulation.

Findings

Strain lifts degeneracy of exciton energy levels.

Control of valley pseudospin achievable at attosecond timescales.

Numerical simulations confirm theoretical predictions.

Abstract

Valleytronics, as an alternative to traditional electronics or spintronics, is based on the encoding of quantum information in pseudospin valley quantum numbers, rather than in charge or spin states. A key ingredient is the (optical) manipulation of valley states before loss of coherence, which can be as fast as 100 femtoseconds. Previous works have shown the possibility of valley state manipulation using external fields. Here we propose uniaxial strain as a more flexible and robust scheme to manipulate the valley state through the breaking of the crystal symmetry and the concomitant lifting of the degeneracy of the 1s exciton energy. Our theory is corroborated by state-of-the-art numerical simulations in monolayer hBN and shows the possibility to control valley pseudospin at the attosecond time scale.