Science Daily August 24, 2023
Quantum light emitters capable of generating single photons with circular polarization and non-classical statistics could enable non-reciprocal single-photon devices and deterministic spin–photon interfaces for quantum networks. The emission of chiral quantum light relies on the application of intense external magnetic fields, electrical/optical injection of spin-polarized carriers/excitons or coupling with complex photonic metastructures. An international team of researchers (USA – Los Alamos National Laboratory, Switzerland) stacked a single-molecule-thick layer of tungsten diselenide semiconductor onto a thicker layer of nickel phosphorus trisulfide magnetic semiconductor and created a series of nanometer-scale indentations on the thin stack of materials. The indentations formed a well, or depression, in the potential energy landscape. Electrons of the tungsten diselenide monolayer fell into the depression and stimulated the emission of a stream of single photons from the well. The quantum light emitters emitted with a high degree of circular polarization (0.89) and single-photon purity (95%), independent of pump laser polarization. They showed that the chiral quantum light emission arose from magnetic proximity interactions between localized excitons in the tungsten diselenide monolayer and the out-of-plane magnetization of defects in the antiferromagnetic order of nickel phosphorus triselenide, both of which were co-localized by strain fields associated with the nanoscale indentations. According to the researchers they have demonstrated a novel approach to control the polarization state of a single photon stream… read more. TECHNICAL ARTICLEÂ
Demonstration of quantum light emission from strain engineered WSe2/NiPS3 heterostructures… Credit: Nature Materials , 17 August 2023Â