@article{48599,
abstract = {{AbstractThe biexciton‐exciton emission cascade commonly used in quantum‐dot systems to generate polarization entanglement yields photons with intrinsically limited indistinguishability. In the present work, it focuses on the generation of pairs of photons with high degrees of polarization entanglement and simultaneously high indistinguishability. It achieves this goal by selectively reducing the biexciton lifetime with an optical resonator. It demonstrates that a suitably tailored circular Bragg reflector fulfills the requirements of sufficient selective Purcell enhancement of biexciton emission paired with spectrally broad photon extraction and twofold degenerate optical modes. The in‐depth theoretical study combines (i) the optimization of realistic photonic structures solving Maxwell's equations from which model parameters are extracted as input for (ii) microscopic simulations of quantum‐dot cavity excitation dynamics with full access to photon properties. It reports non‐trivial dependencies on system parameters and use the predictive power of the combined theoretical approach to determine the optimal range of Purcell enhancement that maximizes indistinguishability and entanglement to near unity values, here specifically for the telecom C‐band at 1550 nm.}},
author = {{Bauch, David and Siebert, Dustin and Jöns, Klaus and Förstner, Jens and Schumacher, Stefan}},
issn = {{2511-9044}},
journal = {{Advanced Quantum Technologies}},
keywords = {{tet_topic_qd}},
publisher = {{Wiley}},
title = {{{On‐Demand Indistinguishable and Entangled Photons Using Tailored Cavity Designs}}},
doi = {{10.1002/qute.202300142}},
year = {{2023}},
}
@unpublished{43246,
abstract = {{The biexciton-exciton emission cascade commonly used in quantum-dot systems to generate polarization entanglement yields photons with intrinsically limited indistinguishability. In the present work we focus on the generation of pairs of photons with high degrees of polarization entanglement and simultaneously high indistinguishibility. We achieve this goal by selectively reducing the biexciton lifetime with an optical resonator. We demonstrate that a suitably tailored circular Bragg reflector fulfills the requirements of sufficient selective Purcell enhancement of biexciton emission paired with spectrally broad photon extraction and two-fold degenerate optical modes. Our in-depth theoretical study combines (i) the optimization of realistic photonic structures solving Maxwell's equations from which model parameters are extracted as input for (ii) microscopic simulations of quantum-dot cavity excitation dynamics with full access to photon properties. We report non-trivial dependencies on system parameters and use the predictive power of our combined theoretical approach to determine the optimal range of Purcell enhancement that maximizes indistinguishability and entanglement to near unity values in the telecom C-band at $1550\,\mathrm{nm}$.}},
author = {{Bauch, David and Siebert, Dustin and Jöns, Klaus and Förstner, Jens and Schumacher, Stefan}},
keywords = {{tet_topic_phc, tet_topic_qd}},
title = {{{On-demand indistinguishable and entangled photons at telecom frequencies using tailored cavity designs}}},
year = {{2023}},
}
@article{27099,
abstract = {{In our work, we have engineered low capacitance single quantum dot photodiodes as sensor devices for the optoelectronic sampling of ultrafast electric signals. By the Stark effect, a time-dependent electric signal is converted into a time-dependent shift of the transition energy. This shift is measured accurately by resonant ps laser spectroscopy with photocurrent detection. In our experiments, we sample the laser synchronous output pulse of an ultrafast CMOS circuit with high resolution. With our quantum dot sensor device, we were able to sample transients below 20 ps with a voltage resolution in the mV-range.}},
author = {{Widhalm, Alex and Krehs, Sebastian and Siebert, Dustin and Sharma, Nand Lal and Langer, Timo and Jonas, Björn and Reuter, Dirk and Thiede, Andreas and Förstner, Jens and Zrenner, Artur}},
issn = {{0003-6951}},
journal = {{Applied Physics Letters}},
keywords = {{tet_topic_qd}},
pages = {{181109}},
title = {{{Optoelectronic sampling of ultrafast electric transients with single quantum dots}}},
doi = {{10.1063/5.0061358}},
volume = {{119}},
year = {{2021}},
}
@article{23816,
abstract = {{Employing the ultrafast control of electronic states of a semiconductor quantum dot in a cavity, we introduce an approach to achieve on-demand emission of single photons with almost perfect indistinguishability and photon pairs with near ideal entanglement. Our scheme is based on optical excitation off resonant to a cavity mode followed by ultrafast control of the electronic states using the time-dependent quantum-confined Stark effect, which then allows for cavity-resonant emission. Our theoretical analysis considers cavity-loss mechanisms, the Stark effect, and phonon-induced dephasing, allowing realistic predictions for finite temperatures.}},
author = {{Bauch, David and Heinze, Dirk Florian and Förstner, Jens and Jöns, Klaus and Schumacher, Stefan}},
issn = {{2469-9950}},
journal = {{Physical Review B}},
keywords = {{tet_topic_qd}},
pages = {{085308}},
title = {{{Ultrafast electric control of cavity mediated single-photon and photon-pair generation with semiconductor quantum dots}}},
doi = {{10.1103/physrevb.104.085308}},
volume = {{104}},
year = {{2021}},
}
@article{17322,
author = {{Mukherjee, Amlan and Widhalm, Alex and Siebert, Dustin and Krehs, Sebastian and Sharma, Nandlal and Thiede, Andreas and Reuter, Dirk and Förstner, Jens and Zrenner, Artur}},
issn = {{0003-6951}},
journal = {{Applied Physics Letters}},
keywords = {{tet_topic_qd}},
pages = {{251103}},
title = {{{Electrically controlled rapid adiabatic passage in a single quantum dot}}},
doi = {{10.1063/5.0012257}},
volume = {{116}},
year = {{2020}},
}
@article{3427,
abstract = {{We report on the coherent phase manipulation of quantum dot excitons by electric means. For our
experiments, we use a low capacitance single quantum dot photodiode which is electrically
controlled by a custom designed SiGe:C BiCMOS chip. The phase manipulation is performed and
quantified in a Ramsey experiment, where ultrafast transient detuning of the exciton energy is
performed synchronous to double pulse p/2 ps laser excitation. We are able to demonstrate
electrically controlled phase manipulations with magnitudes up to 3p within 100 ps which is below
the dephasing time of the quantum dot exciton.}},
author = {{Widhalm, Alex and Mukherjee, Amlan and Krehs, Sebastian and Sharma, Nandlal and Kölling, Peter and Thiede, Andreas and Reuter, Dirk and Förstner, Jens and Zrenner, Artur}},
issn = {{0003-6951}},
journal = {{Applied Physics Letters}},
keywords = {{tet_topic_qd}},
number = {{11}},
pages = {{111105}},
title = {{{Ultrafast electric phase control of a single exciton qubit}}},
doi = {{10.1063/1.5020364}},
volume = {{112}},
year = {{2018}},
}
@article{3888,
abstract = {{We successfully developed a process to fabricate freestanding cubic aluminium nitride (c-AlN) membranes containing cubic gallium nitride (c-GaN) quantum dots (QDs). The samples were grown by plasma assisted molecular beam epitaxy (MBE). To realize the photonic crystal (PhC) membrane we have chosen a triangular array of holes. The array was fabricated by electron beam lithography and several steps of reactive ion etching (RIE) with the help of a hard mask and an undercut of the active layer. The r/a- ratio of 0.35 was deter- mined by numerical simulations to obtain a preferably wide photonic band gap. Micro-photoluminescence (μ-PL) measurements of the photonic crystals, in particular of a H1 and a L3 cavity, and the emission of the QD ensemble were performed to characterize the samples. The PhCs show high quality factors of 4400 for the H1 cavity and about 5000/3000 for two different modes of the L3 cavity, respectively. The energy of the fundamental modes is in good agreement to the numerical simulations. }},
author = {{Blumenthal, Sarah and Bürger, Matthias and Hildebrandt, Andre and Förstner, Jens and Weber, Nils and Meier, Cedrik and Reuter, Dirk and As, Donat J.}},
issn = {{1862-6351}},
journal = {{physica status solidi (c)}},
keywords = {{tet_topic_phc, tet_topic_qd}},
number = {{5-6}},
pages = {{292--296}},
publisher = {{Wiley}},
title = {{{Fabrication and characterization of two-dimensional cubic AlN photonic crystal membranes containing zincblende GaN quantum dots}}},
doi = {{10.1002/pssc.201600010}},
volume = {{13}},
year = {{2016}},
}
@article{3900,
abstract = {{The coherent state preparation and control of single quantum systems is an important prerequisite for the implementation of functional quantum devices. Prominent examples for such systems are semiconductor quantum dots, which exhibit a fine structure split single exciton state and a V-type three level structure, given by a common ground state and two distinguishable and separately excitable transitions. In this work we introduce a novel concept for the preparation of a robust inversion by the sequential excitation in a V-type system via distinguishable paths.}},
author = {{Mantei, D. and Förstner, Jens and Gordon, S. and Leier, Y. A. and Rai, A. K. and Reuter, Dirk and Wieck, A. D. and Zrenner, Artur}},
issn = {{2045-2322}},
journal = {{Scientific Reports}},
keywords = {{tet_topic_qd}},
number = {{1}},
pages = {{10313}},
publisher = {{Springer Nature}},
title = {{{Robust Population Inversion by Polarization Selective Pulsed Excitation}}},
doi = {{10.1038/srep10313}},
volume = {{5}},
year = {{2015}},
}
@misc{4360,
abstract = {{Die Erfindung betrifft ein Verfahren zur Präparation einer Besetzungsinversion in einem Quantensystem (Q) mittels Mehrpulsanregung, wobei ein Quantensystem (Q) umfassend wenigstens einen Quantenpunkt mit zwei orthogonalen Zuständen (/X>, /Y>), insbesondere die mit zueinander orthogonalen Polarisationen (P1, P2) optisch anregbar sind, mit einem ersten Laserpuls (L1) beleuchtet wird, welcher zur resonanten Anregung des ersten (/Y>) der zwei Zustände (/X>, /Y>) eingestellt wird und zeitlich nachfolgend mit einem zweiten Laserpuls (L2) beleuchtet wird, der zur resonanten Anregung des zweiten (/X>) der zwei Zustände (/X>, /Y>) eingestellt wird.}},
author = {{Zrenner, Artur and Förstner, Jens and Mantei, Dirk}},
keywords = {{tet_topic_qd}},
title = {{{A process for the preparation of a population inversion in a quantum system using multi-pulse excitation}}},
year = {{2015}},
}
@article{3959,
abstract = {{Microresonators containing quantum dots find application in devices like single photon emitters for quantum information technology as well as low threshold laser devices. We demonstrate the fabrication of 60 nm thin zinc-blende AlN microdisks including cubic GaN quantum dots using dry chemical etching techniques. Scanning electron microscopy analysis reveals the morphology with smooth surfaces of the microdisks. Micro-photoluminescence measurements exhibit optically active quantum dots. Furthermore this is the first report of resonator modes in the emission spectrum of a cubic AlN microdisk.}},
author = {{Bürger, M. and Kemper, R.M. and Bader, C.A. and Ruth, M. and Declair, S. and Meier, Cedrik and Förstner, Jens and As, D.J.}},
issn = {{0022-0248}},
journal = {{Journal of Crystal Growth}},
keywords = {{tet_topic_qd, tet_topic_microdisk}},
pages = {{287--290}},
publisher = {{Elsevier BV}},
title = {{{Cubic GaN quantum dots embedded in zinc-blende AlN microdisks}}},
doi = {{10.1016/j.jcrysgro.2012.12.058}},
volume = {{378}},
year = {{2013}},
}
@article{3963,
abstract = {{Whispering gallery modes (WGMs) were observed in 60 nm thin cubic AlN microdisk resonators containing a single layer of non-polar cubic GaN quantum dots. Freestanding microdisks were patterned by means of electron beam lithography and a two step reactive ion etching process. Micro-photoluminescence spectroscopy investigations were performed for optical characterization. We analyzed the mode spacing for disk diameters ranging from 2-4 lm. Numerical investigations using three dimensional finite difference time domain calculations were in good agreement
with the experimental data. Whispering gallery modes of the radial orders 1 and 2 were identified by means of simulated mode field distributions.}},
author = {{Bürger, M. and Ruth, M. and Declair, S. and Förstner, Jens and Meier, Cedrik and As, Donat Josef}},
issn = {{0003-6951}},
journal = {{Applied Physics Letters}},
keywords = {{tet_topic_qd, tet_topic_microdisk}},
number = {{8}},
pages = {{081105}},
publisher = {{AIP Publishing}},
title = {{{Whispering gallery modes in zinc-blende AlN microdisks containing non-polar GaN quantum dots}}},
doi = {{10.1063/1.4793653}},
volume = {{102}},
year = {{2013}},
}
@article{3974,
abstract = {{We study the quantum properties and statistics of photons emitted by a quantum-dot biexciton inside a cavity. In the biexciton-exciton cascade, fine-structure splitting between exciton levels degrades polarization-entanglement for the emitted pair of photons. However, here we show that the polarization-entanglement can be preserved in such a system through simultaneous emission of two degenerate photons into cavity modes tuned to half the biexciton energy. Based on detailed theoretical calculations for realistic quantum-dot and cavity parameters, we quantify the degree of achievable entanglement.}},
author = {{Schumacher, Stefan and Förstner, Jens and Zrenner, Artur and Florian, Matthias and Gies, Christopher and Gartner, Paul and Jahnke, Frank}},
issn = {{1094-4087}},
journal = {{Optics Express}},
keywords = {{tet_topic_qd}},
number = {{5}},
pages = {{5335--5342}},
publisher = {{OSA}},
title = {{{Cavity-assisted emission of polarization-entangled photons from biexcitons in quantum dots with fine-structure splitting}}},
doi = {{10.1364/oe.20.005335}},
volume = {{20}},
year = {{2012}},
}
@article{3972,
abstract = {{Using a finite-difference time-domain method, we theoretically investigate the optical spectra of crossing perpendicular photonic crystal waveguides with quantum dots embedded in the central rod. The waveguides are designed so that the light mainly propagates along one direction and the cross talk is greatly reduced in the transverse direction. It is shown that when a quantum dot (QD) is resonant with the cavity, strong coupling can be observed via both the transmission and crosstalk spectrum. If the cavity is far off-resonant from the QD, both the cavity mode and the QD signal can be detected in the transverse direction since the laser field is greatly suppressed in this direction. This structure could have strong implications for resonant excitation and in-plane detection of QD optical spectroscopy.}},
author = {{Song, Xiaohong and Declair, Stefan and Meier, Torsten and Zrenner, Artur and Förstner, Jens}},
issn = {{1094-4087}},
journal = {{Optics Express}},
keywords = {{tet_topic_phc, tet_topic_qd}},
number = {{13}},
pages = {{14130--14136}},
publisher = {{The Optical Society}},
title = {{{Photonic crystal waveguides intersection for resonant quantum dot optical spectroscopy detection}}},
doi = {{10.1364/oe.20.014130}},
volume = {{20}},
year = {{2012}},
}
@misc{4171,
abstract = {{The method involves exciting a quantum system with photons in a polarization state. Two states of the quantum system are excited with linear horizontal and vertical polarizations that are orthogonal to each other, where the states exhibit an energetic gap smaller than energetic bandwidth of photons. The states are assigned based on the polarizations, where the quantum system is arranged in a superposition state. The quantum system is formed by a quantum bit that is formed as a two-level system.}},
author = {{Förstner, Jens and Mantei, D. and de Vasconcellos, S. Michaelis and Zrenner, Artur}},
keywords = {{tet_topic_qd}},
title = {{{Method for transmission of information about polarization state of photons to stationary system}}},
year = {{2011}},
}
@inproceedings{4043,
abstract = {{We present numerical results of the mutual coupling between photonic crystal cavities and semiconductor quantum dots. Normal mode splitting between a single cavity mode and a single quantum dot is shown under weak excitation, while under strong excitation Q‐factor dependent side bands appear, according to the AC‐Stark effect. Coupled photonic crystals, aligned parallel but displaced under a 30°‐angle for efficient coupling, show line splittings of all eigenmodes, if a single eigenmode is resonantly coupled to a single quantum dot. The mutual coupling of N resonant quantum dots to a single cavity mode results in a N−−√
scaling of the splitting, known from quantum optics, but corrected by the field amplitude fraction for not collocated quantum dots.}},
author = {{Declair, S. and Song, X. and Meier, Torsten and Förstner, Jens}},
booktitle = {{THE FOURTH INTERNATIONAL WORKSHOP 2011}},
keywords = {{tet_topic_phc, tet_topic_qd}},
location = {{Bad Honnef}},
number = {{123}},
pages = {{123--125}},
publisher = {{AIP}},
title = {{{Simulation of Mutual Coupling of Photonic Crystal Cavity Modes and Semiconductor Quantum Dots}}},
doi = {{10.1063/1.3644232}},
volume = {{1398}},
year = {{2011}},
}
@article{4089,
abstract = {{We study the influence of the phonon environment on the electron dynamics in a doped quantum dot molecule. A non-perturbative quantumkinetic theory based on correlation expansion is used in order to describe both diagonal and off-diagonal electron-phonon couplings representing real and virtual processes with relevant acoustic phonons. We show that the relaxation is dominated by phononassisted electron tunneling between constituent quantum dots and occurs on a picosecond time scale. The dependence of the time evolution of the quantum dot occupation probabilities on the energy mismatch between the quantum dots is studied in detail.}},
author = {{Grodecka-Grad, Anna and Förstner, Jens}},
issn = {{1862-6351}},
journal = {{physica status solidi (c)}},
keywords = {{tet_topic_qd}},
number = {{4}},
pages = {{1125--1128}},
publisher = {{Wiley}},
title = {{{Phonon-assisted decoherence and tunneling in quantum dot molecules}}},
doi = {{10.1002/pssc.201000824}},
volume = {{8}},
year = {{2011}},
}
@article{4129,
abstract = {{We study a single quantum dot molecule doped with one electron in the presence of electron-phonon coupling. Both diagonal and off-diagonal interactions representing real and virtual processes with acoustic phonons via deformation potential and piezoelectric coupling are taken into account. We employ a non-perturbative quantum kinetic theory and show that the phonon-mediated relaxation is dominated by an electron tunneling on a picosecond time scale.A dependence of the relaxation on the temperature and the strength of the tunneling coupling is analyzed.}},
author = {{Grodecka-Grad, Anna and Förstner, Jens}},
issn = {{1742-6596}},
journal = {{Journal of Physics: Conference Series}},
keywords = {{tet_topic_qd}},
publisher = {{IOP Publishing}},
title = {{{Phonon-mediated relaxation in doped quantum dot molecules}}},
doi = {{10.1088/1742-6596/245/1/012035}},
volume = {{245}},
year = {{2010}},
}
@article{4174,
abstract = {{A quantum dot molecule doped with a single electron in the presence of diagonal and off-diagonal carrierphonon
couplings is studied by means of a nonperturbative quantum kinetic theory. The interaction with acoustic phonons by deformation potential and piezoelectric coupling is taken into account. We show that the phonon-mediated relaxation is fast on a picosecond time scale and is dominated by the usually neglected off-diagonal coupling to the lattice degrees of freedom leading to phonon-assisted electron tunneling. We show that in the parameter regime of current electrical and optical experiments, the microscopic non-Markovian theory has to be employed.}},
author = {{Grodecka-Grad, A. and Förstner, Jens}},
issn = {{1098-0121}},
journal = {{Physical Review B}},
keywords = {{tet_topic_qd}},
number = {{11}},
publisher = {{American Physical Society (APS)}},
title = {{{Theory of phonon-mediated relaxation in doped quantum dot molecules}}},
doi = {{10.1103/physrevb.81.115305}},
volume = {{81}},
year = {{2010}},
}
@article{4123,
abstract = {{GaAs-based semiconductor microdisks with high quality whispering gallery modes (Q44000) have been fabricated.A layer of self-organized InAs quantumdots (QDs) served as a light source to feed the optical modes at room temperature. In order to achieve frequency tuning of the optical modes, the microdisk devices have been immersed in 4 – cyano – 4´-pentylbiphenyl (5CB), a liquid crystal(LC) with a nematic phase below the clearing temperature of TC≈34°C .We have studied the device performance in the temperature rangeof T=20-50°C, in order to investigate the influence of the nematic–isotropic phase transition on the optical modes. Moreover,we havea pplied an AC electric field to the device,which leads in the nematic phase to a reorientation of the anisotropic dielectric tensor of the liquid crystal.This electrical anisotropy can be used to achieve electrical tunability of the optical modes.Using the finite-difference time domain (FDTD) technique with an anisotropic material model, we are able to describe the influence of the liquid crystal qualitatively.}},
author = {{Piegdon, Karoline A. and Offer, Matthias and Lorke, Axel and Urbanski, Martin and Hoischen, Andreas and Kitzerow, Heinz-Siegfried and Declair, Stefan and Förstner, Jens and Meier, Torsten and Reuter, Dirk and Wieck, Andreas D. and Meier, Cedrik}},
issn = {{1386-9477}},
journal = {{Physica E: Low-dimensional Systems and Nanostructures}},
keywords = {{tet_topic_qd, tet_topic_microdisk}},
number = {{10}},
pages = {{2552--2555}},
publisher = {{Elsevier BV}},
title = {{{Self-assembled quantum dots in a liquid-crystal-tunable microdisk resonator}}},
doi = {{10.1016/j.physe.2009.12.051}},
volume = {{42}},
year = {{2010}},
}
@article{4172,
abstract = {{Microdisks made from GaAs with embedded InAs quantum dots are immersed in the liquid crystal 4-cyano-4’-pentylbiphenyl (5CB). The quantum dots serve as emitters feeding the optical modes of the photonic cavity. By changing temperature, the liquid crystal undergoes a phase transition from the isotropic to the nematic state, which can be used
as an effective tuning mechanism of the photonic modes of the cavity. In the nematic state, the uniaxial electrical anisotropy of the liquid crystal molecules can be exploited for orienting the material in an electric field,
thus externally controlling the birefringence of the material. Using this effect, an electric field induced tuning of the modes is achieved. Numerical simulations using the finite-differences time-domain (FDTD) technique
employing an anisotropic dielectric medium allow to understand the alignment of the liquid crystal molecules on the surface of the microdisk resonator.}},
author = {{Piegdon, Karoline A. and Declair, Stefan and Förstner, Jens and Meier, Torsten and Matthias, Heiner and Urbanski, Martin and Kitzerow, Heinz-Siegfried and Reuter, Dirk and Wieck, Andreas D. and Lorke, Axel and Meier, Cedrik}},
issn = {{1094-4087}},
journal = {{Optics Express}},
keywords = {{tet_topic_qd, tet_topic_microdisk}},
number = {{8}},
publisher = {{The Optical Society}},
title = {{{Tuning quantum-dot based photonic devices with liquid crystals}}},
doi = {{10.1364/oe.18.007946}},
volume = {{18}},
year = {{2010}},
}