Single photon emitter deterministically coupled to a topological corner state

Incorporating topological physics into the realm of quantum photonics holds the promise of developing quantum light emitters with inherent topological robustness and immunity to backscattering.Nonetheless,the deterministic interaction of quantum emitters with topologically nontrivial resonances remains largely unexplored.Here we present a single photon emitter that utilizes a single semiconductor quantum dot,deterministically coupled to a second-order topological corner state in a photonic crystal cavity.By investigating the Purcell enhancement of both single photon count and emission rate within this topological cavity,we achieve an experimental Purcell factor of Fp=3.7.Furthermore,we demonstrate the on-demand emission of polarized single photons,with a second-order autocorrelation function g(2)(0)as low as 0.024±0.103.Our approach facilitates the customization of light-matter interactions in topologically nontrivial environments,thereby offering promising applications in the field of quantum photonics.

Tunable quantum dots in monolithic Fabry-Perot microcavities for high-performance single-photon sources

Cavity-enhanced single quantum dots(QDs)are the main approach towards ultra-high-performance solid-state quantum light sources for scalable photonic quantum technologies.Nevertheless,harnessing the Purcell effect requires precise spectral and spatial alignment of the QDs’emission with the cavity mode,which is challenging for most cavities.Here we have successfully integrated miniaturized Fabry-Perot microcavities with a piezoelectric actuator,and demonstrated a bright single-photon source derived from a deterministically coupled QD within this microcavity.Leveraging the cavity-membrane structures,we have achieved large spectral tunability via strain tuning.On resonance,a high Purcell factor of~9 is attained.The source delivers single photons with simultaneous high extraction efficiency of 0.58,high purity of 0.956(2)and high indistinguishability of 0.922(4).Together with its compact footprint,our scheme facilitates the scalable integration of indistinguishable quantum light sources on-chip,therefore removing a major barrier to the development of solid-state quantum information platforms based on QDs.

Effective integration of highly-efficient focusing apodized grating and quantum dots on a solid substrate for scalable quantum photonic circuits

Recent advancements in quantum photonic circuits have significantly influenced the field of quantum information processing.The pursuit of an integrated quantum photonic circuit that offers an active,stable platform for large-scale integration and high processing efficiency remains a key objective.The grating coupler,as a crucial element for an efficient transformation output interface in the integrated quantum photonic circuits,presents significant potential for practical applications.Here,we demonstrate the integration block of a highly efficient shallow-etched focusing apodized grating coupler with indium arsenide(InAs)quantum dots(QDs)in gallium arsenide(GaAs)on a SiO2substrate for active quantum photonic circuits.The designed grating couplers possess a high efficiency over 90% in the broadband(900-930 nm)from the circuit to free space,and a nearly-perfect match with the fiber mode.Experimentally,the efficiency to free space reaches 81.8%,and the match degree with the fiber mode is high up to 92.1%.The proposed integration block offers the potential for large-scale integration of active quantum photonic circuits due to its stable solid substrate and highly performant output for quantum measurements.

Bright semiconductor single-photon sources pumped by heterogeneously integrated micropillar lasers with electrical injections

The emerging hybrid integrated quantum photonics combines the advantages of different functional components into a single chip to meet the stringent requirements for quantum information processing.Despite the tremendous progress in hybrid integrations of III-V quantum emitters with silicon-based photonic circuits and superconducting single-photon detectors,on-chip optical excitations of quantum emitters via miniaturized lasers towards single-photon sources(SPSs)with low power consumptions,small device footprints,and excellent coherence properties is highly desirable yet illusive.In this work,we present realizations of bright semiconductor SPSs heterogeneously integrated with on-chip electrically-injected microlasers.Different from previous one-by-one transfer printing technique implemented in hybrid quantum dot(QD)photonic devices,multiple deterministically coupled QD-circular Bragg Grating(CBG)SPSs were integrated with electrically-injected micropillar lasers at one time via a potentially scalable transfer printing process assisted by the wide-field photoluminescence(PL)imaging technique.Optically pumped by electrically-injected microlasers,pure single photons are generated with a high-brightness of a count rate of 3.8 M/s and an extraction efficiency of 25.44%.Such a high-brightness is due to the enhancement by the cavity mode of the CBG,which is confirmed by a Purcell factor of 2.5.Our work provides a powerful tool for advancing hybrid integrated quantum photonics in general and boosts the developments for realizing highly-compact,energy-efficient and coherent SPSs in particular.

Filter-free high-performance single-photon emission from a quantum dot in a Fabry–Perot microcavity

Combining resonant excitation with Purcell-enhanced single quantum dots(QDs)stands out as a prominent strategy for realizing high-performance solid-state single-photon sources.However,optimizing photon extraction efficiency requires addressing the challenge of effectively separating the excitation laser from the QDs’emission.Traditionally,this involves polarization filtering,limiting the achievable polarization directions and the scalability of polarized photonic states.In this study,we have successfully tackled this challenge by employing spatially orthogonal resonant excitation of QDs,deterministically coupled to monolithic Fabry–Perot microcavities.Leveraging the planar microcavity structure,we have achieved spectral filter-free single-photon resonant fluorescence.The resulting source produces single photons with a high extraction efficiency of 0.87 and an indistinguishability of 0.963(4).

Inter-facet composition modulation of III-nitride nanowires over pyramid textured Si substrates by stationary molecular beam epitaxy

InGaN nanowires (NWs) are grown on pyramid textured Si substrates by stationary plasma-assisted molecular beam epitaxy (PA-MBE). The incidence angles of the highly directional source beams vary for different pyramid facets, inducing a distinct inter-facet modulation of the In content of the InGaN NWs, which is verified by spatial element distribution analysis. The resulting multi-wavelength emission is confirmed by photoluminescence (PL) and cathodoluminescence (CL). Pure GaN phase formation dominates on certain facets, which is attributed to extreme local growth conditions, such as low active N flux. On the same facets, InGaN NWs exhibit a morphology change close to the pyramid ridge, indicating inter-facet atom migration. This cross-talk effect due to inter-facet atom migration is verified by a decrease of the inter-facet In content modulation amplitude with shrinking pyramid size. A detailed analysis of the In content variation across individual pyramid facets and element distribution line profiles reveals that the cross-talk effect originates mainly from the inter-facet atom migration over the convex pyramid ridge facet boundaries rather than the concave base line facet boundaries. This is understood by first-principles calculations showing that the pyramid baseline facet boundary acts as an energy barrier for atom migration, which is much higher than that of the ridge facet boundary. The influence of the growth temperature on the inter-facet In content modulation is also presented. This work gives deep insight into the composition modulation for the realization of multi-color light-emitting devices based on the monolithic growth of InGaN NWs on pyramid textured Si substrates.