Optical control of a single spin-valley in charged WSe${}_2$ quantum dots

Abstract

Control and manipulation of single charges and their internal degrees of freedom, such as spins, is a fundamental goal of nanoscience with promising technological applications. Recently, atomically thin semiconductors such as WSe${}_2$ have emerged as a platform for valleytronics, offering rich possibilities for optical, magnetic and electrical control of the valley index. While progress has been made in controlling valley index of ensemble of charge carriers, valley control of individual charges, crucial for valleytronics, remains unexplored. Here, we provide unambiguous evidence for localized holes with net spin in optically active WSe${}_2$ quantum dots (QDs) and control their spin-valley state with the helicity of the excitation laser under small magnetic field. We estimate a lower bound on the valley lifetime of a single charge in QD from recombination time to be $\sim$ nanoseconds. Remarkably, neutral QDs do not exhibit such a control, demonstrating the role of excess charge in prolonging the valley lifetime. Our work extends the field of 2D valleytronics to the level of single spin-valley, relevant for quantum information and sensing applications

References in corpus (24)

• Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
• Control of valley polarization in monolayer MoS2 by optical helicity
• Advances in Quantum Metrology
• Valley polarization in MoS2 monolayers by optical pumping
• MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect
• Magnetic Control of Valley Pseudospin in Monolayer WSe2
• Valley Zeeman Effect in Elementary Optical Excitations of a Monolayer WSe2
• Breaking of valley degeneracy by magnetic field in monolayer MoSe2
• Large-scale quantum-emitter arrays in atomically thin semiconductors
• Deterministic strain-induced arrays of quantum emitters in a two-dimensional semiconductor
• Valley Splitting and Polarization by the Zeeman Effect in Monolayer MoSe2
• Bright excitons in monolayer transition metal dichalcogenides: from Dirac cones to Dirac saddle points
• Exciton Diamagnetic Shifts and Valley Zeeman Effects in Monolayer WS${}_2$ and MoS${}_2$ to 65 Tesla
• Long-lived nanosecond spin relaxation and spin coherence of electrons in monolayer MoS_2 and WS_2
• Charged excitons in monolayer WSe${}_2$: experiment and theory
• Voltage-Controlled Optics of a Quantum Dot
• Observation of Faraday rotation from a single confined spin
• Microsecond dark-exciton valley polarization memory in 2D heterostructures
• Gate controlled spin-valley locking of resident carriers in WSe2 monolayers
• Optical spectroscopy of single quantum dots at tunable positive, neutral and negative charge states
• Electrically pumped single-defect light emitters in WSe${}_2$
• Spin-valley qubit in nanostructures of monolayer semiconductors: Optical control and hyperfine interaction
• Long valley lifetime of free carriers in monolayer WSe2
• Interplay of valley polarization and dynamic nuclear polarization in 2D transition metal dichalcogenides

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• Dipolar interactions between field-tuneable, localized emitters in van der Waals heterostructures
• Localized inter-valley defect excitons as single-photon emitters in WSe${}_2$
• Site-Controlled Telecom Single-Photon Emitters in Atomically-thin MoTe2
• Nanomaterials for Quantum Information Science and Engineering
• Long valley lifetime of dark excitons in single-layer WSe2
• Identifying defect-related quantum emitters in monolayer WSe${}_2$
• Exciton optics, dynamics and transport in atomically thin semiconductors
• Excited-state spin-resonance spectroscopy of V${}_{\text{B}}^{-}$ defect centers in hexagonal boron nitride
• Dielectrics for Two-Dimensional Transition Metal Dichalcogenide Applications
• Spin-defect characteristics of single sulfur vacancies in monolayer ${\text{MoS}}_2$
• Spin splitting and strain in epitaxial monolayer WSe${}_2$ on graphene
• Gate-defined, Accumulation-mode Quantum Dots in Monolayer and Bilayer WSe${}_2$
• The effect of valley, spin and band nesting on the electronic properties of gated quantum dots in a single layer of transition metal dichalcogenides (TMDCs)
• Valley-selective energy transfer between quantum dots in atomically thin semiconductors
• Single charge control of localized excitons in heterostructures with ferroelectric thin films and two-dimensional transition metal dichalcogenides
• Spin-valley qubits in gated quantum dots in a single layer of transition metal dichalcogenides