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

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.

5 pages, 4 figures

References in corpus (13)

• Two Dimensional Atomic Crystals
• Valley polarization in MoS2 monolayers by optical pumping
• Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Valley filter and valley valve in graphene
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
• Valley Zeeman Effect in Elementary Optical Excitations of a Monolayer WSe2
• Breaking of valley degeneracy by magnetic field in monolayer MoSe2
• Ultrafast Generation of Pseudo-magnetic Field for Valley Excitons in WSe2 Monolayers
• Ultrafast Manipulation of Valley Pseudospin
• Control of Exciton Valley Coherence in Transition Metal Dichalcogenide Monolayers
• Valley splitting of AlAs two-dimensional electrons in a perpendicular magnetic field
• Valley polarization and susceptibility of composite fermions around nu=3/2