Search query: Optical emission from a charge-tunable quantum ring

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abstract: Quantum dots or rings are artificial nanometre sized clusters that confine electrons in all three directions. They can be fabricated in a semiconductor system by embedding an island of low bandgap material in a sea of material with a higher bandgap. Quantum dots are often referred to as artificial atoms because, when filled sequentially with electrons, the charging energies are pronounced for particular electron numbers; this is analogous to Hund's rules in atomic physics. But semiconductors also have a valence band with strong optical transitions to the conduction band. These transitions are the basis for the application of quantum dots as laser emitters, storage devices and fluorescence markers. Here we report how the optical emission (photoluminescence) of a single quantum ring changes as electrons are added one by one. We find that the emission energy changes abruptly whenever an electron is added to the artificial atom, and that the sizes of the jumps reveal a shell structure.
author_names: Richard John Warburton

C Schaflein

D Haft

F Bickel

Axel Lorke

Khaled Karrai

J M Garcia

Winston V Schoenfeld

P M Petroff
title: Optical emission from a charge tunable quantum ring
venue: Nature
year: 2000

abstract: Irradiating intercalated nanorings by optical vortices ignites a charge flow that emits coherent trains of high harmonic bursts with frequencies and time structures that are controllable by the topological charge of the driving vortex beam. Similar to synchrotron radiation, the polarization of emitted harmonics is also selectable by tuning to the appropriate emission angle with respect to the ring plane. The nonequilibrium orbital magnetic moment triggered in a ring tunnels quantum mechanically to smaller and larger rings leading respectively to high and low frequency harmonic generation. The frequencies of the emitted harmonics are tunable by simply changing the waist and/or the winding number of the optical vortex, without the need to increase the pulse intensity which can lead to material damage. These findings follow from full fledged quantum dynamic simulations for realistic material and laser parameters. The proposed setup is non destructive as only short vortex pulses of moderate intensities are needed, and it offers a versatile tool for nanoscale optical and spectroscopic applications such as local, single beam pump probe experiments.
author_names: Jonas Watzel

Jamal Berakdar
title: Tunable high harmonic pulses from nanorings swirled by optical vortices.
venue: Optics express
year: 2017

abstract: The N 2 aryl 1,2,3 triazole derivatives (NATs) were developed as a new class of UV/blue light emitting fluorophores. Though both N 1 aryl 1,2,3 triazoles and N 2 aryl 1,2,3 triazoles gave strong photo absorption under excitation at 330 nm, only the N 2 analogous showed strong fluorescence emission in the UV/blue range with high efficiency in various solvents (quantum yield Ph around 0.3 0.5) Significant substituted group effects were observed, allowing tunable optical properties with emission (l(max) from 350 400 nm and Stokes shift from 38 93 nm. The computational studies along with X ray crystal structures indicated the significance of the effective conjugation between triazole ring and aryl groups on the N 2 position. The planar intramolecular charge transfer (PICT) mechanism was proposed, which was supported by solvent effect studies. Simple derivatizations gave NAT modified lysine and strong UV/blue emitting bis NAT (Ph=0.76, l(max)=390) which suggested the great potential of this new class of fluorophores in biological and material science research.
author_names: Wuming Yan

Qiaoyi Wang

Quan Lin

Minyong Li

Jeffrey L Petersen

Xiaodong Shi
title: N 2 aryl 1,2,3 triazoles: a novel class of UV/blue light emitting fluorophores with tunable optical properties.
venue: Chemistry
year: 2011

abstract: Abstract We have succeeded in preparing excitons with a specific charge in single semiconductor quantum rings. Buried InAs quantum rings are loaded with electrons from a reservoir through a tunneling barrier and an additional electron hole pair is generated by optical excitation. Single rings are addressed with nano optical techniques. We observe abrupt shifts in the emission energy as electrons are added one by one. Furthermore, the experiments provide unique insights into the interaction of electrons in semiconductor nano islands with their environment.
author_names: Richard John Warburton

C Schaflein

D Haft

F Bickel

Axel Lorke

Khaled Karrai

Jorge M Garcia

Winston V Schoenfeld

P M Petroff
title: Optical emission from single, charge tunable quantum rings
year: 2001

abstract: We have succeeded in preparing excitons with a speci c charge in single semiconductor quantum rings. Buried InAs quantum rings are loaded with electrons from a reservoir through a tunneling barrier and an additional electron hole pair is generated by optical excitation. Single rings are addressed with nano optical techniques. We observe abrupt shifts in the emission energy as electrons are added one by one. Furthermore, the experiments provide unique insights into the interaction of electrons in semiconductor nano islands with their environment. 2001 Elsevier Science B.V. All rights reserved.
author_names: R J Warburtona

D Hafta

F Bickela

Andreas Lorkea

K Karraia

J M Garciab

W V Schoenfeldb

P M Petro
title: Optical emission from single charge tunable quantum rings
year: 2000

abstract: We show that one dimensional (1d) GaN quantum wires (QWRs) exhibit intense and spectrally sharp emission lines. These QWRs are realized in an entirely self assembled growth process by molecular beam epitaxy (MBE) on the side facets of GaN/AlN nanowire (NW) heterostructures. Time integrated and time resolved photoluminescence (PL) data in combination with numerical calculations allow the identification and assignment of the manifold emission features to three different spatial recombination centers within the NWs. The recombination processes in the QWRs are driven by efficient charge carrier transfer effects between the different optically active regions, providing high intense QWR luminescence despite their small volume. This is deduced by a fast rise time of the QWR PL, which is similar to the fast decay time of adjacent carrier reservoirs. Such processes, feeding the ultra narrow QWRs with carriers from the relatively large NWs, can be the key feature towards the realization of future QWR based devices. While processing of single quantum structures with diameters in the nm range presents a serious obstacle with respect to their integration into electronic or photonic devices, the QWRs presented here can be analyzed and processed using existing techniques developed for single NWs.
author_names: Jan Mussener

Ludwig A Th Greif

Stefan Kalinowski

Gordon Callsen

Pascal Hille

Jorg Schormann

M R Wagner

Andrei Schliwa

Sara Marti-Sanchez

Jordi Arbiol

Axel Hoffmann

Martin Eickhoff
title: Optical emission of GaN/AlN quantum wires the role of charge transfer from a nanowire template.
venue: Nanoscale
year: 2018

abstract: Abstract The capture cross section, intersubband optical cross section and non radiative emission rates related to localized hole states are obtained for p i n solar cells containing GaSb/GaAs quantum rings embedded within the i region of the device. The technique developed uses the intraband photoemission current to probe the charge state of the nanostructures during two color excitation. Analysis of the excitation power dependence revealed a non radiative hole capture lifetime of 12 ns under low excitation conditions, with high injection leading to the saturation of the hole occupancy within the quantum rings. The decay characteristics of the optical hole emission current has also been exploited to determine the spectral and temperature dependence of the radiative and non radiative hole escape mechanisms from the quantum rings.
author_names: Magnus C Wagener

Denise Montesdeoca

Qi Lu

Andrew R J Marshall

Anthony Krier

Johannes Reinhardt Botha

Peter J Carrington
title: Hole capture and emission dynamics of type II GaSb/GaAs quantum ring solar cells
year: 2019

abstract: We demonstrate full charge control, narrow optical linewidths, and optical spin pumping on single self assembled InGaAs quantum dots embedded in a $162.5\\text{nm} thin diode structure. The quantum dots are just $88\\text{nm} from the top GaAs surface. We design and realize a p i n i n diode that allows single electron charging of the quantum dots at close to zero applied bias. In operation, the current flow through the device is extremely small resulting in low noise. In resonance fluorescence, we measure optical linewidths below $2\\mu\text{eV} just a factor of two above the transform limit. Clear optical spin pumping is observed in a magnetic field of $0.5\\text{T} in the Faraday geometry. We present this design as ideal for securing the advantages of self assembled quantum dots highly coherent single photon generation, ultra fast optical spin manipulation in the thin diodes required in quantum nano photonics and nano phononics applications.
author_names: Matthias C Lobl

Immo Sollner

Alisa Javadi

Tommaso Pregnolato

Rudiger Schott

Leonardo Midolo

A V Kuhlmann

Soren Stobbe

Andreas Dirk Wieck

Peter Lodahl

Arne Ludwig

Richard John Warburton
title: Narrow optical linewidths and spin pumping on charge tunable close to surface self assembled quantum dots in an ultrathin diode
year: 2017

abstract: Perovskite quantum emitters The development of many optical quantum technologies is dependent on the availability of solid state single quantum emitters with near perfect optical coherence. Light emitting defects in diamond and quantum dots grown by molecular beam epitaxy have demonstrated transform limited emission linewidths. However, they are limited in terms of production scalability and reproducibility between individual emitters. Utzat et al. now show that perovskite quantum dots can overcome these limitations and provide unprecedented versatility for the generation of indistinguishable single photons or entangled photon pairs for quantum information processing. Science, this issue p. 1068 Perovskite quantum dots could be used as scalable quantum emitters for quantum information processing. Chemically made colloidal semiconductor quantum dots have long been proposed as scalable and color tunable single emitters in quantum optics, but they have typically suffered from prohibitively incoherent emission. We now demonstrate that individual colloidal lead halide perovskite quantum dots (PQDs) display highly efficient single photon emission with optical coherence times as long as 80 picoseconds, an appreciable fraction of their 210 picosecond radiative lifetimes. These measurements suggest that PQDs should be explored as building blocks in sources of indistinguishable single photons and entangled photon pairs. Our results present a starting point for the rational design of lead halide perovskite based quantum emitters that have fast emission, wide spectral tunability, and scalable production and that benefit from the hybrid integration with nanophotonic components that has been demonstrated for colloidal materials.
author_names: Hendrik Utzat

Weiwei Sun

Alexander E K Kaplan

Franziska Krieg

Matthias Ginterseder

Boris Spokoyny

Nathan D Klein

Katherine E Shulenberger

Collin F Perkinson

Maksym V Kovalenko

Moungi G Bawendi
title: Coherent single photon emission from colloidal lead halide perovskite quantum dots
venue: Science
year: 2019

abstract: We report on the optical properties of single InAs/GaAs quantum dots emitting near the telecommunication O band, probed via Coulomb blockade and nonresonant photoluminescence spectroscopy, in the presence of external electric and magnetic fields. We extract the physical properties of the electron and hole wave functions, including the confinement energies, interaction energies, wave function lengths, and g factors. For excitons, we measure the permanent dipole moment, polarizability, diamagnetic coefficient, and Zeeman splitting. The carriers are determined to be in the strong confinement regime. Large range electric field tunability, up to 7 meV, is demonstrated for excitons. We observe a large reduction, up to one order of magnitude, in the diamagnetic coefficient when rotating the magnetic field from Faraday to Voigt geometry due to the unique dot morphology. The complete spectroscopic characterization of the fundamental properties of long wavelength dot in a well structures provides insight for the applicability of quantum technologies based on quantum dots emitting at telecom wavelengths.
author_names: Luca Sapienza

Rima Al-Khuzheyri

Adetunmise C Dada

Andrew Griffiths

Edmund Clarke

Brian D Gerardot
title: Magneto optical spectroscopy of single charge tunable InAs/GaAs quantum dots emitting at telecom wavelengths
year: 2016