Magnetically tunable exciton valley coherence in monolayer WS${}_2$ mediated by the electron-hole exchange and exciton-phonon interactions

Abstract

We develop a model, which incorporates both intra- and intervalley scatterings to master equation, to explore exciton valley coherence in monolayer WS${}_2$ subjected to magnetic field. For linearly polarized (LP) excitation accompanied with an initial coherence, our determined valley dynamics manifests the coherence decay being faster than the exciton population relaxation, and agrees with experimental data by Hao et al.[Nat. Phys. 12, 677 (2016)]. Further, we reveal that magnetic field may quench the electron-hole (e-h) exchange induced pure dephasing -- a crucial decoherence source -- as a result of lifting of valley degeneracy, allowing to magnetically regulate valley coherence. In particular, at low temperatures for which the exciton-phonon (ex-ph) interaction is weak, we find that the coherence time is expected to attain ${\tau }_{\mathcal{C}}\sim 1$ ps, facilitating full control of qubits based on the valley pseudospin. For dark excitons, we demonstrate an emerging coherence even in the absence of initial coherent state, which has a long coherence time ($\sim 15$ ps) at low temperature. Our work provides an insight into tunable valley coherence and coherent valley control based on dark excitons.

arXiv comment7 pages, 4 figures

References in corpus (47)

• Two Dimensional Atomic Crystals
• Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
• Valley polarization in MoS2 monolayers by optical pumping
• Quantifying Coherence
• 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
• Measure for the Degree of Non-Markovian Behavior of Quantum Processes in Open Systems
• Optical Generation of Excitonic Valley Coherence in Monolayer WSe2
• Tightly bound excitons in monolayer WSe2
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
• Magnetic Control of Valley Pseudospin in Monolayer WSe2
• Environment-Assisted Quantum Transport
• Semiconductor Spintronics
• Intrinsic Exciton Linewidth in Monolayer Transition Metal Dichalcogenides
• Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides
• Exciton Radiative Lifetime in Transition Metal Dichalcogenide Monolayers
• Intrinsic Electrical Transport Properties of Monolayer Silicene and MoS2 from First Principles
• Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2
• Carrier and polarization dynamics in monolayer MoS2
• Valley depolarization due to inter- and intra-valley electron-hole exchange interactions in monolayer MoS${}_2$
• Long-lived nanosecond spin relaxation and spin coherence of electrons in monolayer MoS_2 and WS_2
• Direct Measurement of Exciton Valley Coherence in Monolayer WSe${}_2$
• Ultrafast Manipulation of Valley Pseudospin
• Nonlinear Photoluminescence in Atomically Thin Layered WSe2 Arising from Diffusion-Assisted Exciton-Exciton Annihilation
• Fine Structure and Lifetime of Dark Excitons in Transition Metal Dichalcogenide Monolayers
• Control of Exciton Valley Coherence in Transition Metal Dichalcogenide Monolayers
• Microsecond Valley Lifetime of Defect-Bound Excitons in Monolayer WSe${}_2$
• Control of the Exciton Radiative Lifetime in van der Waals Heterostructures
• Gate controlled spin-valley locking of resident carriers in WSe2 monolayers
• Exciton g-factors of van der Waals heterostructures from first principles calculations
• Zeeman Splitting and Inverted Polarization of Biexciton Emission in Monolayer WS2
• Exciton-exciton interaction in transition metal dichalcogenide monolayers and van der Waals heterostructures
• Ab-initio studies of exciton $g$ factors: Monolayer transition metal dichalcogenides in magnetic fields
• Dark excitons and the elusive valley polarization in transition metal dichalcogenides
• Probing and manipulating valley coherence of dark excitons in monolayer WSe${}_2$
• Double resonant Raman scattering and valley coherence generation in monolayer WSe2
• Measurement of Conduction and Valence Bands g-factors in a Transition Metal Dichalcogenide Monolayer
• Observation of exciton-exciton interaction mediated valley depolarization in monolayer MoSe${}_2$
• Theory of coupled spin-charge transport due to spin-orbit interaction in inhomogeneous two-dimensional electron liquids
• Superior valley polarization and coherence of 2s excitons in monolayer WSe2
• Intervalley Scattering of Interlayer Excitons in a MoS${}_2$/MoSe${}_2$/MoS${}_2$ Heterostructure in High Magnetic Field
• Phonon-assisted inter-valley scattering determines ultrafast exciton dynamics in MoSe${}_2$ bilayers
• Strong Valley Zeeman Effect of Dark Excitons in Monolayer Transition Metal Dichalcogenides in a Tilted Magnetic Field
• Enhancement of Exciton Valley Polarization in Monolayer MoS2 Induced by Scattering
• Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time
• Controlling valley splitting and Polarization of dark- and bi-excitons in monolayer WS${}_2$ by a tilted magnetic field
• Spin drift-diffusion for two-subband quantum wells

Cited by in corpus (2)

• Laser-field detuning assisted optimization of exciton valley dynamics in monolayer WSe${}_2$: Geometric quantum speed limit
• Ellipticity-Controlled Bright-Dark Coherence Transition in Monolayer WSe2