Optical resonators are a powerful platform to control the spontaneous emission dynamics of excitons in solidstate nanostructures.We study a MoSe_(2)-WSe_(2)heterostructure that is integrated in a cryogenic open optica...Optical resonators are a powerful platform to control the spontaneous emission dynamics of excitons in solidstate nanostructures.We study a MoSe_(2)-WSe_(2)heterostructure that is integrated in a cryogenic open optical microcavity to gain insights into fundamental optical properties of the emergent interlayer excitons.First,we utilize a low-quality-factor planar open cavity and investigate the modification of the excitonic lifetime as on-and offresonance conditions are met with consecutive longitudinal modes.Time-resolved photoluminescence measurements revealed a periodic tuning of the interlayer exciton lifetime by 220 ps,which allows us to extract a 0.5 ns free-space radiative lifetime and a quantum efficiency as high as 81.4%±1.4%.We subsequently engineer the local density of optical states by spatially confined and spectrally tunable Tamm-plasmon resonances.The dramatic redistribution of the local optical modes allows us to encounter a significant inhibition of the excitonic spontaneous emission rate by a factor of 3.2.Our open cavity is able to tune the cavity resonances accurately to the emitters to have a robust in situ control of the light-matter coupling.Such a powerful characterization approach can be universally applied to tune the exciton dynamics and measure the quantum efficiencies of more complex van der Waals heterostructures and devices.展开更多
Measured and calculated results are presented for the emission properties of a new class of emitters operating in the cavity quantum electrodynamics regime.The structures are based on high-finesse GaAs/AlAs micropilla...Measured and calculated results are presented for the emission properties of a new class of emitters operating in the cavity quantum electrodynamics regime.The structures are based on high-finesse GaAs/AlAs micropillar cavities,each with an active medium consisting of a layer of InGaAs quantum dots(QDs)and the distinguishing feature of having a substantial fraction of spontaneous emission channeled into one cavity mode(highβ-factor).This paper demonstrates that the usual criterion for lasing with a conventional(lowβ-factor)cavity,that is,a sharp non-linearity in the input–output curve accompanied by noticeable linewidth narrowing,has to be reinforced by the equal-time second-order photon autocorrelation function to confirm lasing.The paper also shows that the equal-time second-order photon autocorrelation function is useful for recognizing superradiance,a manifestation of the correlations possible in high-βmicrocavities operating with QDs.In terms of consolidating the collected data and identifying the physics underlying laser action,both theory and experiment suggest a sole dependence on intracavity photon number.Evidence for this assertion comes from all our measured and calculated data on emission coherence and fluctuation,for devices ranging from light-emitting diodes(LEDs)and cavity-enhanced LEDs to lasers,lying on the same two curves:one for linewidth narrowing versus intracavity photon number and the other for g(2)(0)versus intracavity photon number.展开更多
GaN nanowires have been grown by molecular beam epitaxy either catalyst-free or catalyst-induced by means of Ni seeds.Under identical growth conditions of temperature andⅤ/Ⅲratio,both types of GaN nanowires are of w...GaN nanowires have been grown by molecular beam epitaxy either catalyst-free or catalyst-induced by means of Ni seeds.Under identical growth conditions of temperature andⅤ/Ⅲratio,both types of GaN nanowires are of wurtzite structure elongated in the Ga-polar direction and are constricted by M-plane facets.However,the catalyst-induced nanowires contain many more basal-plane stacking faults and their photoluminescence is weaker.These differences can be explained as effects of the catalyst Ni seeds.展开更多
Future quantum technology relies crucially on building quantum networks with high fidelity.To achieve this challenging goal,it is of utmost importance to connect individual quantum systems such that their emitted sing...Future quantum technology relies crucially on building quantum networks with high fidelity.To achieve this challenging goal,it is of utmost importance to connect individual quantum systems such that their emitted single photons overlap with the highest possible degree of coherence.This requires perfect mode overlap of the emitted light from different emitters,which necessitates the use of single-mode fibres.Here,we present an advanced manufacturing approach to accomplish this task.We combined 3D printed complex micro-optics,such as hemispherical and Weierstrass solid immersion lenses,as well as total internal reflection solid immersion lenses,on top of individual indium arsenide quantum dots with 3D printed optics on single-mode fibres and compared their key features.We observed a systematic increase in the collection efficiency under variations of the lens geometry from roughly 2 for hemispheric solid immersion lenses up to a maximum of greater than 9 for the total internal reflection geometry.Furthermore,the temperature-induced stress was estimated for these particular lens dimensions and results to be approximately 5 meV.Interestingly,the use of solid immersion lenses further increased the localisation accuracy of the emitters to less than 1 nm when acquiring micro-photoluminescence maps.Furthermore,we show that the single-photon character of the source is preserved after device fabrication,reaching a g^((2))(0)value of approximately 0.19 under pulsed optical excitation.The printed lens device can be further joined with an optical fibre and permanently fixed.This integrated system can be cooled by dipping into liquid helium using a Stirling cryocooler or by a closed-cycle helium cryostat without the necessity for optical windows,as all access is through the integrated single-mode fibre.We identify the ideal optical designs and present experiments that demonstrate excellent high-rate single-photon emission.展开更多
Two-level emitters are the main building blocks of photonic quantum technologies and are model systems for the exploration of quantum optics in the solid state.Most interesting is the strict resonant excitation of suc...Two-level emitters are the main building blocks of photonic quantum technologies and are model systems for the exploration of quantum optics in the solid state.Most interesting is the strict resonant excitation of such emitters to control their occupation coherently and to generate close to ideal quantum light,which is of utmost importance for applications in photonic quantum technology.To date,the approaches and experiments in this field have been performed exclusively using bulky lasers,which hinders the application of resonantly driven two-level emitters in compact photonic quantum systems.Here we address this issue and present a concept for a compact resonantly driven single-photon source by performing quantum-optical spectroscopy of a two-level system using a compact high-βmicrolaser as the excitation source.The two-level system is based on a semiconductor quantum dot(QD),which is excited resonantly by a fiber-coupled electrically driven micropillar laser.We dress the excitonic state of the QD under continuous wave excitation,and trigger the emission of single photons with strong multi-photon suppression(ge2Te0T?0:02)and high photon indistinguishability(V=57±9%)via pulsed resonant excitation at 156 MHz.These results clearly demonstrate the high potential of our resonant excitation scheme,which can pave the way for compact electrically driven quantum light sources with excellent quantum properties to enable the implementation of advanced quantum communication protocols.展开更多
文摘Optical resonators are a powerful platform to control the spontaneous emission dynamics of excitons in solidstate nanostructures.We study a MoSe_(2)-WSe_(2)heterostructure that is integrated in a cryogenic open optical microcavity to gain insights into fundamental optical properties of the emergent interlayer excitons.First,we utilize a low-quality-factor planar open cavity and investigate the modification of the excitonic lifetime as on-and offresonance conditions are met with consecutive longitudinal modes.Time-resolved photoluminescence measurements revealed a periodic tuning of the interlayer exciton lifetime by 220 ps,which allows us to extract a 0.5 ns free-space radiative lifetime and a quantum efficiency as high as 81.4%±1.4%.We subsequently engineer the local density of optical states by spatially confined and spectrally tunable Tamm-plasmon resonances.The dramatic redistribution of the local optical modes allows us to encounter a significant inhibition of the excitonic spontaneous emission rate by a factor of 3.2.Our open cavity is able to tune the cavity resonances accurately to the emitters to have a robust in situ control of the light-matter coupling.Such a powerful characterization approach can be universally applied to tune the exciton dynamics and measure the quantum efficiencies of more complex van der Waals heterostructures and devices.
基金the European Research Council under the Seventh Framework ERC Grant Agreement No.615613 of the European Unionthe German Research Foundation via the projects RE2974/5-1,Ka23187-1 and JA 619/10-3+3 种基金the US Department of Energy under Contract No.DE-AC04-94AL85000the Technical University Berlin for hospitality and the German Research Foundation via collaborative research center 787 for travel supportsupport from the German Science Foundation(DFG)support from the German Federal Ministry of Education and Research(BMBF).
文摘Measured and calculated results are presented for the emission properties of a new class of emitters operating in the cavity quantum electrodynamics regime.The structures are based on high-finesse GaAs/AlAs micropillar cavities,each with an active medium consisting of a layer of InGaAs quantum dots(QDs)and the distinguishing feature of having a substantial fraction of spontaneous emission channeled into one cavity mode(highβ-factor).This paper demonstrates that the usual criterion for lasing with a conventional(lowβ-factor)cavity,that is,a sharp non-linearity in the input–output curve accompanied by noticeable linewidth narrowing,has to be reinforced by the equal-time second-order photon autocorrelation function to confirm lasing.The paper also shows that the equal-time second-order photon autocorrelation function is useful for recognizing superradiance,a manifestation of the correlations possible in high-βmicrocavities operating with QDs.In terms of consolidating the collected data and identifying the physics underlying laser action,both theory and experiment suggest a sole dependence on intracavity photon number.Evidence for this assertion comes from all our measured and calculated data on emission coherence and fluctuation,for devices ranging from light-emitting diodes(LEDs)and cavity-enhanced LEDs to lasers,lying on the same two curves:one for linewidth narrowing versus intracavity photon number and the other for g(2)(0)versus intracavity photon number.
基金This work has been supported by the EU through the IST project NODE(No.015783)the Marie Curie RTN PARSEM(MRTN-CT-2004-005583).
文摘GaN nanowires have been grown by molecular beam epitaxy either catalyst-free or catalyst-induced by means of Ni seeds.Under identical growth conditions of temperature andⅤ/Ⅲratio,both types of GaN nanowires are of wurtzite structure elongated in the Ga-polar direction and are constricted by M-plane facets.However,the catalyst-induced nanowires contain many more basal-plane stacking faults and their photoluminescence is weaker.These differences can be explained as effects of the catalyst Ni seeds.
基金We acknowledge the financial support of the German Federal Ministry of Science and Education[Bundesministerium fur Bildung und Forschung(BMBF)]via the projects Printoptics,Printfunction,and Q.link.X 16KIS0862support via the project EMPIR 17FUN06 SIQUST+1 种基金This project received funding from Baden-Württemberg-Stiftung via the Opterial projectThis project received funding from the EMPIR programme co-financed by the participating states and from the European Union’s Horizon 2020 research and innovation programme.Furthermore,funding was received from the European Research Council(ERC)via the projects AdG ComplexPlas and PoC 3D PrintedOptics.It was also funded by the Deutsche Forschungsgemeinschaft(DFG)via the projects SPP1839,SPP1929,GRK2642,as well as the Center for Integrated Quantum Science and Technology(IQST).
文摘Future quantum technology relies crucially on building quantum networks with high fidelity.To achieve this challenging goal,it is of utmost importance to connect individual quantum systems such that their emitted single photons overlap with the highest possible degree of coherence.This requires perfect mode overlap of the emitted light from different emitters,which necessitates the use of single-mode fibres.Here,we present an advanced manufacturing approach to accomplish this task.We combined 3D printed complex micro-optics,such as hemispherical and Weierstrass solid immersion lenses,as well as total internal reflection solid immersion lenses,on top of individual indium arsenide quantum dots with 3D printed optics on single-mode fibres and compared their key features.We observed a systematic increase in the collection efficiency under variations of the lens geometry from roughly 2 for hemispheric solid immersion lenses up to a maximum of greater than 9 for the total internal reflection geometry.Furthermore,the temperature-induced stress was estimated for these particular lens dimensions and results to be approximately 5 meV.Interestingly,the use of solid immersion lenses further increased the localisation accuracy of the emitters to less than 1 nm when acquiring micro-photoluminescence maps.Furthermore,we show that the single-photon character of the source is preserved after device fabrication,reaching a g^((2))(0)value of approximately 0.19 under pulsed optical excitation.The printed lens device can be further joined with an optical fibre and permanently fixed.This integrated system can be cooled by dipping into liquid helium using a Stirling cryocooler or by a closed-cycle helium cryostat without the necessity for optical windows,as all access is through the integrated single-mode fibre.We identify the ideal optical designs and present experiments that demonstrate excellent high-rate single-photon emission.
基金funding from the European Research Council(ERC)under the European Union’s Seventh Framework ERC Grant Agreement No.615613the German Research Foundation(DFG)via CRC 787 and Projects No.RE2974/5-1,RE2974/9-1,and SCHN1376/2-1+1 种基金the State of Bavaria,and the German Ministry of Education and Research(BMBF)the support of the DFG through the project B1 of the SFB 910.
文摘Two-level emitters are the main building blocks of photonic quantum technologies and are model systems for the exploration of quantum optics in the solid state.Most interesting is the strict resonant excitation of such emitters to control their occupation coherently and to generate close to ideal quantum light,which is of utmost importance for applications in photonic quantum technology.To date,the approaches and experiments in this field have been performed exclusively using bulky lasers,which hinders the application of resonantly driven two-level emitters in compact photonic quantum systems.Here we address this issue and present a concept for a compact resonantly driven single-photon source by performing quantum-optical spectroscopy of a two-level system using a compact high-βmicrolaser as the excitation source.The two-level system is based on a semiconductor quantum dot(QD),which is excited resonantly by a fiber-coupled electrically driven micropillar laser.We dress the excitonic state of the QD under continuous wave excitation,and trigger the emission of single photons with strong multi-photon suppression(ge2Te0T?0:02)and high photon indistinguishability(V=57±9%)via pulsed resonant excitation at 156 MHz.These results clearly demonstrate the high potential of our resonant excitation scheme,which can pave the way for compact electrically driven quantum light sources with excellent quantum properties to enable the implementation of advanced quantum communication protocols.
