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The interaction between the charge carrier spin of a quantum dot (QD) exciton and photons enables the transfer of quantum information between separate quantum emitters, which lays the foundation of a scalable, photon-mediated quantum spin network[1]. With a specially designed spin-photon interface, the exciton spin could be coupled to the propagation direction of the photons scattered from the emitter via the chiral light-matter interaction[2]. Following up the work in ref.[3], here we demonstrate strong Purcell enhancement and high directionality for individual QDs embedded in a glide-plane photonic crystal waveguide (GPW). Additionally, by leveraging the spin preservation of p-shell quasi-resonant excitation, we successfully initialise an exciton spin on-chip. We have recorded a dramatic increase in chirality when a QD is driven in-plane and achieved a near-unity chiral contrast in the transmission geometry. This indicates a polarisation-dependent spin transfer between the QD and the waveguide mode. Besides, the directional coupling also gives rise to a non-linear single-photon phase shift, forming the basis for scalable quantum phase gates and other on-chip spin-photonics applications in chiral quantum optics[4].
References :
[1] Warburton R. J. et al. Single spins in self-assembled quantum dots. Nat. Mater. 12, 483–493 (2013).
[2] Lodahl P. et al. Chiral quantum optics. Nature 541, 473–480 (2017).
[3] Siampour H. et al. Observation of large spontaneous emission rate enhancement of quantum dots in a bro-ken-symmetry slow-light waveguide. npj Quantum Information, 9, 15 (2023).
[4] Dietrich, C. P. et al. GaAs integrated quantum photonics: Towards compact and multi-functional quantum photonic integrated circuits. Laser Photonics Rev. 10, 870–894 (2016).
