Delaying tunable single photons from a quantum dot with an atomic ensemble

InAsP quantum dots embedded in InP nanowires are manufactured to have an emission around the D1 line of cesium (894 nm) and can serve as a bright source of single photons. To interface these photons with atoms, their wavelength has to be controlled with precision that is usually not considered in experiments involving solid-state emitters. To overcome this, we have recently discovered a method of tuning the photon frequency via gas deposition. To characterize the quality of this tunability, we measure the delay experienced by these photons passing through a vapor cell of cesium atoms. Here, we report theoretical estimates and experimental observations of delay of a broadband (~1 GHz) single photons as they transmit through a cloud of warm cesium vapor.