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  1. Abstract

    Chiral single photons are highly sought to enhance encoding capacities or enable propagation-dependent routing in nonreciprocal devices. Unfortunately, most semiconductor quantum emitters (QEs) produce only linear polarized photons unless external magnets are applied. Magnetic proximity coupling utilizing 2D ferromagnets promises to make bulky external fields obsolete. Here we directly grow Fe-doped MoS2(Fe:MoS2) via chemical vapor deposition that displays pronounced hard ferromagnetic properties even in monolayer form. This approach with monolayer ferromagnets enables full utilization of the strain from the pillar stressor to form QE in WSe2deterministically. The Fe:MoS2/WSe2heterostructures display strong hysteretic magneto-response and high-purity chiral single photons with a circular polarization degree of 92 ± 1% (74% average) without external magnetic fields. Furthermore, the chiral single photons are robust against uncontrolled twist-angle and external stray-fields. This ability to manipulate quantum states and transform linear polarized photons into high-purity chiral photons on-chip enables nonreciprocal device integration in quantum photonics.

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  2. Light carries both spin angular momentum (SAM) and orbital angular momentum (OAM), which can be used as potential degrees of freedom for quantum information processing. Quantum emitters are ideal candidates towards on-chip control and manipulation of the full SAM–OAM state space. Here, we show coupling of a spin-polarized quantum emitter in a monolayerWSe2with the whispering gallery mode of aSi3N4ring resonator. The cavity mode carries a transverse SAM ofσ<#comment/>=±<#comment/>1in the evanescent regions, with the sign depending on the orbital power flow direction of the light. By tailoring the cavity–emitter interaction, we couple the intrinsic spin state of the quantum emitter to the SAM and propagation direction of the cavity mode, which leads to spin–orbit locking and subsequent chiral single-photon emission. Furthermore, by engineering how light is scattered from the WGM, we create a high-order Bessel beam which opens up the possibility to generate optical vortex carrying OAM states.

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  3. null (Ed.)
    van der Waals ferromagnets have gained significant interest due to their unique ability to provide magnetic response even at the level of a few monolayers. Particularly in combination with 2D semiconductors, such as the transition metal dichalcogenide WSe 2 , one can create heterostructures that feature unique magneto-optical response in the exciton emission through the magnetic proximity effect. Here we use 0D quantum emitters in WSe 2 to probe for the ferromagnetic response in heterostructures with Fe 3 GT and Fe 5 GT ferromagnets through an all-optical read-out technique that does not require electrodes. The spectrally narrow spin-doublet of the WSe 2 quantum emitters allowed to fully resolve the hysteretic magneto-response in the exciton emission, revealing the characteristic signature of both ferro- and antiferromagnetic proximity coupling that originates from the interplay among Fe 3 GT or Fe 5 GT, a thin surface oxide, and the spin doublets of the quantum emitters. Our work highlights the utility of 0D quantum emitters for probing interface magnetic dipoles in vdW heterostructures with high precision. The observed hysteretic magneto response in the exciton emission of quantum emitters adds further new degrees of freedom for spin and g -factor manipulation of quantum states. 
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