We demonstrate storage of excitons in a single nanostructure, a self-assembled Quantum Post. Afte... more We demonstrate storage of excitons in a single nanostructure, a self-assembled Quantum Post. After generation electron and holes forming the exciton are separated by an electric field towards opposite ends of the Quantum Post inhibiting their radiative recombination. After a defined time such spatially indirect excitons are reconverted to optically active direct excitons by switching the electric field. The emitted light of the stored exciton is detected in the limit of a single nanostructure and storage times exceeding 30 msec are demonstrated. We identify a slow tunneling of the electron out of the Quantum Post as the dominant loss mechanism by comparing the field dependent temporal decay of the storage signal to models for this process and radiative losses.
Com miss ion, nor any of their emp loye es, nor any of their cont racto rs, subc ontra ctors , or... more Com miss ion, nor any of their emp loye es, nor any of their cont racto rs, subc ontra ctors , or their emp loyee s, make s any warr anty , expr ess or imp lied, or assu mes any iegal liabi lity or resp ons ibilit y for the accu racy , complete ness or usef ulne ss of any infor mati on, appa ratus , wou ld not infrin ge priva tely owne d right s. pro duc t or proc ess disc lose d, or repr esen ts that its use BIST RIBU TION OF THIS DOC UME NT IS UNL IMm m 0,+A-L DISCLAIMER
A single quantum dot strongly coupled to a photonic crystal nanocavity can completely modify its ... more A single quantum dot strongly coupled to a photonic crystal nanocavity can completely modify its transmission, from transparent to opaque for an optical beam on the cavity resonance, as we have recently demonstrated in the InAs/GaAs system (Fig. 1) [1]. This is a result of the ...
We present the first radiative lifetime measurements and magneto-photoluminescence results of exc... more We present the first radiative lifetime measurements and magneto-photoluminescence results of excited states in InGaAs/GaAs semiconductor self-assembled quantum dots. By increasing the photo-excitation intensity, excited state interband transitions up to n = 5 can be observed in the emission spectrum. The dynamics of the interband transitions and the inter-sublevel relaxation in these zero-dimensional energy levels lead to state-filling of the lower-energy states, allowing the quasi-Fermi level to be raised by more than 200 meV due to the combined large inter-sublevel spacing and the low density of states. The decay time of each energy level obtained under various excitation conditions is used to evaluate the inter-sublevel thermalization time. Finally, the emission spectrum of the dots filled with an average of about eight excitons is measured in magnetic fields up to 13 Tesla. The dependences of the spectrum as a function of carrier density and magnetic field are compared to calculations and interpreted in terms of coherent many-exciton states and their destruction by the magnetic field.
It is shown by transmission electron microscopy (TEM) investigation that the dark line defect (DL... more It is shown by transmission electron microscopy (TEM) investigation that the dark line defect (DLD) structure induced by optical pumping of undoped Ga1-xAlxAs-GaAs double-heterostructure (DH) laser material is identical to the DLD's which develop during laser diode operation of devices fabricated from similar p-n structure material. This confirms the DLD generation, and subsequent failure of cw laser diodes can be
We apply diffraction limited confocal optical microscopy to spatially resolve a single self assem... more We apply diffraction limited confocal optical microscopy to spatially resolve a single self assembled semiconductor quantum dot (SAQD). The photoluminescence intensity as a function of photon energy and position along a line scan across the SAQD sample surface, shows clearly the emission from separate dots, approximately 0.7 mu m apart. At relatively low excitation power, up to 0.5 mW, the
The emission spectrum of self-assembled InGaAs/GaAs quantum dots filled with up to 10 excitions i... more The emission spectrum of self-assembled InGaAs/GaAs quantum dots filled with up to 10 excitions is measured in magnetic fields up to 13 Tesla. The spectrum shows a number of peaks which split and rearrange with the magnetic field. The behaviour of the spectrum with carrier density and magnetic field is compared with detailed calculations. The model allows us to interpret our results in terms of coherent many-exciton states and their destruction by the magnetic field. The level structure of the spectra is related to the shell structure and collective excitations of many-excition droplets in these artificial atoms.
Quantum dots (QDs) coupled to the optical modes of photonic crystal devices represent one of the ... more Quantum dots (QDs) coupled to the optical modes of photonic crystal devices represent one of the most promising platforms for future optical networks for classical and quantum information processing. One of the main components for these nano-photonic devices is an ...
Spectroscopy of Nanoscopic Semiconductor Rings. Axel Lorke, R. Johannes Luyken * , Alexander O. G... more Spectroscopy of Nanoscopic Semiconductor Rings. Axel Lorke, R. Johannes Luyken * , Alexander O. Govorov , and Jörg P. Kotthaus Sektion Physik und CeNS, LMU München, Geschwister-Scholl-Platz 1, 80539 München, Germany. ...
A photoluminescence study of self-assembled InAs/ GaAs quantum dots under the influence of magnet... more A photoluminescence study of self-assembled InAs/ GaAs quantum dots under the influence of magnetic fields perpendicular and parallel to the dot layer is presented. At low temperatures, the magnetic field perpendicular to the dot layer alters the in-plane transport properties due to localization of carriers in wetting layer ͑WL͒ potential fluctuations. Decreased transport in the WL results in a reduced capture into the quantum dots and consequently a weakened dot-related emission. The effect of the magnetic field exhibits a considerable dot density dependence, which confirms the correlation to the in-plane transport properties. An interesting effect is observed at temperatures above approximately 100 K, for which magnetic fields, both perpendicular and parallel to the dot layer, induced an increment of the quantum dot photoluminescence. This effect is ascribed to the magnetic confinement of the exciton wave function, which increases the probability for carrier capture and localization in the dot, but affects also the radiative recombination with a reduced radiative lifetime in the dots under magnetic compression.
Indium Phosphide and Related Materials Conference, 2003
Pure photoluminescence spectra originating from a single InAs/GaAs quantum dot, which is small en... more Pure photoluminescence spectra originating from a single InAs/GaAs quantum dot, which is small enough to possess only one single-electron level, are demonstrated. A symmetric fine structure of the exciton and the biexciton is observed.
A microphotoluminescence study of single InAs/GaAs quantum dots ͑QDs͒ in the presence of an appli... more A microphotoluminescence study of single InAs/GaAs quantum dots ͑QDs͒ in the presence of an applied external magnetic field is presented. Attention is focused on the redistribution between the spectral lines of a single QD observed at increasing magnetic field parallel to the growth direction ͑Faraday geometry͒. The redistribution effect is explained by considering the electron drift velocity in the QD plane that affects the probability for capture into the QD. In contrast, no redistribution is observed when applying the magnetic field perpendicular to the growth direction ͑Voigt geometry͒.
We study dynamics of the interaction between two weak light beams mediated by a strongly coupled ... more We study dynamics of the interaction between two weak light beams mediated by a strongly coupled quantum dot-photonic crystal cavity system. First, we perform all optical switching of a weak continuous-wave signal with a pulsed control beam, and then perform switching between two pulsed beams (40ps pulses) at the single photon level. Our results show that the quantum dot-nanocavity system creates strong, controllable interactions at the single photon level.
A photonic crystal cavity with a strongly coupled quantum dot is coherently driven using short la... more A photonic crystal cavity with a strongly coupled quantum dot is coherently driven using short laser pulses. Depending on the driving frequency, photon blockade or photon induced tunneling is observed. These nonlinear phenomena at single photon level are used for on-chip generation of nonclassical light.
Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot. E. Dekel 1 , D. Gershoni 1 , E.... more Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot. E. Dekel 1 , D. Gershoni 1 , E. Ehrenfreund 1 , D. Spektor 1 , JM Garcia 2 , and PM Petroff 2 1 Physics Department and Solid State Institute, Technion-Israel ...
Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot. E. Dekel 1 , D. Gershoni 1 , E.... more Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot. E. Dekel 1 , D. Gershoni 1 , E. Ehrenfreund 1 , D. Spektor 1 , JM Garcia 2 , and PM Petroff 2 1 Physics Department and Solid State Institute, Technion-Israel ...
We demonstrate storage of excitons in a single nanostructure, a self-assembled Quantum Post. Afte... more We demonstrate storage of excitons in a single nanostructure, a self-assembled Quantum Post. After generation electron and holes forming the exciton are separated by an electric field towards opposite ends of the Quantum Post inhibiting their radiative recombination. After a defined time such spatially indirect excitons are reconverted to optically active direct excitons by switching the electric field. The emitted light of the stored exciton is detected in the limit of a single nanostructure and storage times exceeding 30 msec are demonstrated. We identify a slow tunneling of the electron out of the Quantum Post as the dominant loss mechanism by comparing the field dependent temporal decay of the storage signal to models for this process and radiative losses.
Com miss ion, nor any of their emp loye es, nor any of their cont racto rs, subc ontra ctors , or... more Com miss ion, nor any of their emp loye es, nor any of their cont racto rs, subc ontra ctors , or their emp loyee s, make s any warr anty , expr ess or imp lied, or assu mes any iegal liabi lity or resp ons ibilit y for the accu racy , complete ness or usef ulne ss of any infor mati on, appa ratus , wou ld not infrin ge priva tely owne d right s. pro duc t or proc ess disc lose d, or repr esen ts that its use BIST RIBU TION OF THIS DOC UME NT IS UNL IMm m 0,+A-L DISCLAIMER
A single quantum dot strongly coupled to a photonic crystal nanocavity can completely modify its ... more A single quantum dot strongly coupled to a photonic crystal nanocavity can completely modify its transmission, from transparent to opaque for an optical beam on the cavity resonance, as we have recently demonstrated in the InAs/GaAs system (Fig. 1) [1]. This is a result of the ...
We present the first radiative lifetime measurements and magneto-photoluminescence results of exc... more We present the first radiative lifetime measurements and magneto-photoluminescence results of excited states in InGaAs/GaAs semiconductor self-assembled quantum dots. By increasing the photo-excitation intensity, excited state interband transitions up to n = 5 can be observed in the emission spectrum. The dynamics of the interband transitions and the inter-sublevel relaxation in these zero-dimensional energy levels lead to state-filling of the lower-energy states, allowing the quasi-Fermi level to be raised by more than 200 meV due to the combined large inter-sublevel spacing and the low density of states. The decay time of each energy level obtained under various excitation conditions is used to evaluate the inter-sublevel thermalization time. Finally, the emission spectrum of the dots filled with an average of about eight excitons is measured in magnetic fields up to 13 Tesla. The dependences of the spectrum as a function of carrier density and magnetic field are compared to calculations and interpreted in terms of coherent many-exciton states and their destruction by the magnetic field.
It is shown by transmission electron microscopy (TEM) investigation that the dark line defect (DL... more It is shown by transmission electron microscopy (TEM) investigation that the dark line defect (DLD) structure induced by optical pumping of undoped Ga1-xAlxAs-GaAs double-heterostructure (DH) laser material is identical to the DLD's which develop during laser diode operation of devices fabricated from similar p-n structure material. This confirms the DLD generation, and subsequent failure of cw laser diodes can be
We apply diffraction limited confocal optical microscopy to spatially resolve a single self assem... more We apply diffraction limited confocal optical microscopy to spatially resolve a single self assembled semiconductor quantum dot (SAQD). The photoluminescence intensity as a function of photon energy and position along a line scan across the SAQD sample surface, shows clearly the emission from separate dots, approximately 0.7 mu m apart. At relatively low excitation power, up to 0.5 mW, the
The emission spectrum of self-assembled InGaAs/GaAs quantum dots filled with up to 10 excitions i... more The emission spectrum of self-assembled InGaAs/GaAs quantum dots filled with up to 10 excitions is measured in magnetic fields up to 13 Tesla. The spectrum shows a number of peaks which split and rearrange with the magnetic field. The behaviour of the spectrum with carrier density and magnetic field is compared with detailed calculations. The model allows us to interpret our results in terms of coherent many-exciton states and their destruction by the magnetic field. The level structure of the spectra is related to the shell structure and collective excitations of many-excition droplets in these artificial atoms.
Quantum dots (QDs) coupled to the optical modes of photonic crystal devices represent one of the ... more Quantum dots (QDs) coupled to the optical modes of photonic crystal devices represent one of the most promising platforms for future optical networks for classical and quantum information processing. One of the main components for these nano-photonic devices is an ...
Spectroscopy of Nanoscopic Semiconductor Rings. Axel Lorke, R. Johannes Luyken * , Alexander O. G... more Spectroscopy of Nanoscopic Semiconductor Rings. Axel Lorke, R. Johannes Luyken * , Alexander O. Govorov , and Jörg P. Kotthaus Sektion Physik und CeNS, LMU München, Geschwister-Scholl-Platz 1, 80539 München, Germany. ...
A photoluminescence study of self-assembled InAs/ GaAs quantum dots under the influence of magnet... more A photoluminescence study of self-assembled InAs/ GaAs quantum dots under the influence of magnetic fields perpendicular and parallel to the dot layer is presented. At low temperatures, the magnetic field perpendicular to the dot layer alters the in-plane transport properties due to localization of carriers in wetting layer ͑WL͒ potential fluctuations. Decreased transport in the WL results in a reduced capture into the quantum dots and consequently a weakened dot-related emission. The effect of the magnetic field exhibits a considerable dot density dependence, which confirms the correlation to the in-plane transport properties. An interesting effect is observed at temperatures above approximately 100 K, for which magnetic fields, both perpendicular and parallel to the dot layer, induced an increment of the quantum dot photoluminescence. This effect is ascribed to the magnetic confinement of the exciton wave function, which increases the probability for carrier capture and localization in the dot, but affects also the radiative recombination with a reduced radiative lifetime in the dots under magnetic compression.
Indium Phosphide and Related Materials Conference, 2003
Pure photoluminescence spectra originating from a single InAs/GaAs quantum dot, which is small en... more Pure photoluminescence spectra originating from a single InAs/GaAs quantum dot, which is small enough to possess only one single-electron level, are demonstrated. A symmetric fine structure of the exciton and the biexciton is observed.
A microphotoluminescence study of single InAs/GaAs quantum dots ͑QDs͒ in the presence of an appli... more A microphotoluminescence study of single InAs/GaAs quantum dots ͑QDs͒ in the presence of an applied external magnetic field is presented. Attention is focused on the redistribution between the spectral lines of a single QD observed at increasing magnetic field parallel to the growth direction ͑Faraday geometry͒. The redistribution effect is explained by considering the electron drift velocity in the QD plane that affects the probability for capture into the QD. In contrast, no redistribution is observed when applying the magnetic field perpendicular to the growth direction ͑Voigt geometry͒.
We study dynamics of the interaction between two weak light beams mediated by a strongly coupled ... more We study dynamics of the interaction between two weak light beams mediated by a strongly coupled quantum dot-photonic crystal cavity system. First, we perform all optical switching of a weak continuous-wave signal with a pulsed control beam, and then perform switching between two pulsed beams (40ps pulses) at the single photon level. Our results show that the quantum dot-nanocavity system creates strong, controllable interactions at the single photon level.
A photonic crystal cavity with a strongly coupled quantum dot is coherently driven using short la... more A photonic crystal cavity with a strongly coupled quantum dot is coherently driven using short laser pulses. Depending on the driving frequency, photon blockade or photon induced tunneling is observed. These nonlinear phenomena at single photon level are used for on-chip generation of nonclassical light.
Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot. E. Dekel 1 , D. Gershoni 1 , E.... more Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot. E. Dekel 1 , D. Gershoni 1 , E. Ehrenfreund 1 , D. Spektor 1 , JM Garcia 2 , and PM Petroff 2 1 Physics Department and Solid State Institute, Technion-Israel ...
Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot. E. Dekel 1 , D. Gershoni 1 , E.... more Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot. E. Dekel 1 , D. Gershoni 1 , E. Ehrenfreund 1 , D. Spektor 1 , JM Garcia 2 , and PM Petroff 2 1 Physics Department and Solid State Institute, Technion-Israel ...
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