Electrical manipulation of valley-qubit and valley geometric phase in lateral monolayer heterostructures

Abstract

We explore a solid state qubit defined on valley isospin of an electron confined in a gate-defined quantum dot created in an area of monolayer MoS$_2$/WS$_2$ lateral junction, where a steep dipolar potential emerges. We show that the junction oriented along an armchair direction can induce intervalley transitions of the electron confined in the neighboring quantum dot when the (gate-controllable) overlapping with the junction is significant and pumping frequency tuned. The pumping scheme that induces transitions is all-electrical: obtained by applying oscillating voltages to control gates and thus enables for scalable qubit architectures. We also report another possibility of valley-qubit manipulation by accumulating non-Abelian valley Berry phase. To model nanodevice we solve the time-dependent Schr\"odinger-Poisson equations in a tight-binding approach and obtain exact time-evolution of the valley-qubit system.