# Experimental valley qubit state tomography and coherence induced uncertainty relations in monolayer WSe$_2$

## TL;DR

This paper explores valley qubit state tomography in monolayer WSe$_2$, demonstrating experimental techniques to accurately determine qubit states and investigating coherence effects on uncertainty relations in valleytronics.

## Contribution

It presents the first experimental implementation of valley qubit state tomography in monolayer WSe$_2$, advancing the control and measurement of valley pseudospins for quantum information.

## Key findings

- Successful valley qubit state tomography in monolayer WSe$_2$
- Observation of coherence effects on uncertainty relations
- Enhanced understanding of valley pseudospin control

## Abstract

Velleytronics as a new electronic conception is an emerging exciting research field with wide potential applications, which is attracting great research interests for their extraordinary properties. The localized electronic spins by optical generation of valley polarization with spin-like quantum numbers are promising candidates for implementing quantum-information processing in solids. It is expected that a single qubit preparation can be realized optically by using combination of left- and right-circularly polarized lights. Significantly in a series of experiments, this has already been well achieved by linearly polarized laser representing equal weights of left- and right-circular components resulting in formation of a valley exciton as a specific pseudo-spin qubit with equal amplitudes for spin up and spin down. Further researches on the control of valley pseudospin using longitudinal magnetic field and optical Stark effect have been reported. However, a general qubit preparation has not yet been demonstrated. Moreover as a platform for quantum information processing, the precise readout of a qubit state is necessary, for which the state tomography is a standard method in obtaining all information of a qubit state density matrix.