A5046845172- Semiconductor Quantum Structures and Devices
- Photonic and Optical Devices
- Semiconductor Lasers and Optical Devices
- Quantum Information and Cryptography
- Quantum and electron transport phenomena
- Photonic Crystals and Applications
- Neural Networks and Reservoir Computing
- Fuel Cells and Related Materials
- Mechanical and Optical Resonators
- Molecular Junctions and Nanostructures
- Electrocatalysts for Energy Conversion
- Advanced Photonic Communication Systems
- Spectroscopy and Quantum Chemical Studies
- Quantum optics and atomic interactions
- Advanced Fiber Laser Technologies
- Nanofabrication and Lithography Techniques
- Optical Coatings and Gratings
- Surface Roughness and Optical Measurements
- Conducting polymers and applications
- Advancements in Semiconductor Devices and Circuit Design
- Near-Field Optical Microscopy
- Advanced Battery Technologies Research
- Optical Network Technologies
- Integrated Circuits and Semiconductor Failure Analysis
- Semiconductor materials and devices
Technische Universität Berlin
2018-2024
Fraunhofer Institute for Solar Energy Systems
2020-2023
The development of multi-node quantum optical circuits has attracted great attention in recent years. In particular, interfacing quantum-light sources, gates and detectors on a single chip is highly desirable for the realization large networks. this context, fabrication techniques that enable deterministic integration pre-selected emitters into nanophotonic elements play key role when moving forward to containing multiple emitters. Here, we present an InAs dot 50/50 multi-mode interference...
Silicon photonics enables scaling of quantum photonic systems by allowing the creation extensive, low-loss, reconfigurable networks linking various functional on-chip elements. Inclusion single emitters onto circuits, acting as on-demand sources indistinguishable photons or single-photon nonlinearities, may enable large-scale chip-based circuits and networks. Toward this, we use low-temperature in situ electron-beam lithography to deterministically produce hybrid GaAs/Si3N4 devices...
To advance the technology of polymer electrolyte membrane fuel cells, material development is at forefront research. This especially true for electrode assembly, where structuring its various layers has proven to be directly linked performance increase. In this study, we investigate influence ingredients in cathode catalyst layer, such as ionomer content, loading and type, on oxygen ion transport using a full parametric analysis. Using two types catalysts, 40 wt.% Pt/C 60 with high surface...
We report on the epitaxial growth, theoretical modeling, and structural as well optical investigation of multi-layer, site-controlled quantum dots fabricated using buried stressor method. This deterministic growth technique utilizes strain from a partially oxidized AlAs layer to induce site-selective nucleation InGaAs dots. By implementing strain-induced spectral nano-engineering, we achieve control emission local increase in emitter density. Furthermore, threefold intensity reduce...
The realization of efficient quantum light sources relies on the integration self-assembled dots (QDs) into photonic nanostructures with a spectral alignment high spatial positioning accuracy. In this work, we present comprehensive investigation QD position accuracy, obtained using two marker-based techniques, photoluminescence (PL) and cathodoluminescence (CL) imaging, as well marker-free in situ electron beam lithography (in EBL) technique. We employ four PL imaging configurations three...
Integrated quantum photonic circuits (IQPCs) with deterministically integrated emitters are critical elements for scalable information applications and have attracted significant attention in recent years. However, scaling them up toward fully functional multiple to generate input states remains a great challenge. In this work, we report on monolithic prototype IQPC consisting of two preselected dots into nanobeam cavities at the ports 2 × multimode interference beam splitter. The on-chip...
Cavity-enhanced emission of electrically controlled semiconductor quantum dots (QDs) is essential in the development bright devices for real-world photonic applications. Combining circular Bragg grating (CBG) approach with a PIN-diode structure, we propose and implement designs ridge-based contacted QD-CBG resonators. Through fine-tuning device parameters numerical simulations deterministic nanoprocessing, produced single resonators excellent electro-optical properties. These include...
We report on the experimental study and numerical analysis of chiral light-matter coupling in deterministically fabricated quantum dot (QD) waveguide structures. apply situ electron beam lithography to integrate single InGaAs/GaAs QDs into GaAs-DBR waveguides systematically explore dependence position QD inside waveguide. By a series microphotoluminescence measurements, we determine directionality contrast emission left right traveling modes revealing maximum 0.93 for highly off-center...
Self-organized semiconductor quantum dots represent almost ideal two-level systems, which have strong potential to applications in photonic technologies. For instance, they can act as emitters close-to-ideal light sources. Coupled dot systems with significantly increased functionality are potentially of even stronger interest since be used host ultra-stable singlet-triplet spin qubits for efficient spin-photon interfaces and a deterministic 2D cluster-state generation. We realize an advanced...
We report on the deterministic fabrication of high-performance hybrid circular Bragg gratings (hCBGs) with embedded InAs/GaAs quantum dots and their direct permanent fiber-pigtailing to single mode fibers. The devices exhibit spontaneous emission lifetimes <50ps resulting in experimental Purcell factor well beyond 15. fiber-pigtailed show excellent temperature stability unprecedented performance terms photon purity.
We present Purcell-enhanced (FP > 25) semiconductor InAs quantum dot decay times of T1 < 30 ps, enabled by deterministic hybrid circular Bragg gratings (hCBGs). investigate the benefits these short T1-times on two-photon indistinguishability for quasi-resonant and strictly resonant excitation observe visibilities ≥96% at 12.5 ns time delay consecutively emitted photons. The strongly enable a high degree elevated temperatures up to K and, moreover, allow 1.28 GHz repetition rate. Our work...
We report on the design of nanohole/nanobeam cavities in ridge waveguides for on-chip, quantum-dot-based single-photon generation. Our overcomes limitations a low-refractive-index-contrast material platform terms emitter-mode coupling efficiency and yields an outcoupling 0.73 to output waveguide. Importantly, this high is combined with broadband operation 9 nm full-width half-maximum. provide explicit procedure identifying optimum geometrical parameters according developed design. Besides,...
We report on the deterministic fabrication of quantum devices aided by machine-learning-based image processing. The goal work is to demonstrate that pattern recognition based specifically trained machine learning (ML) algorithms and applying it luminescence maps can strongly enhance capabilities modern technologies rely a precise determination positions emitters like, for instance, in situ lithography techniques. In present case, we apply electron beam (EBL) deterministically integrate...
Semiconductor quantum dot molecules are considered promising candidates for technological applications due to their wide tunability of optical properties and coverage different energy scales associated with charge spin physics. While previous works have studied the tunnel-coupling excitonic complexes shared by two dots conventional spectroscopy, we here report on first demonstration a coherently controlled interdot focusing coherence optically active trion transitions. We employ ultrafast...
With in situ electron beam lithography we deterministically integrate single InAs quantum dots into hybrid GaAs/Si3N4 waveguide circuits. We show on-chip dot emission of single, post-selected indistinguishable photons Si3N4 waveguides.
Quantum dot molecules (QDMs) are one of the few quantum light sources that promise deterministic generation one- and two-dimensional photonic graph states. The proposed protocols rely on coherent excitation tunnel-coupled spatially indirect exciton Here, we demonstrate power-dependent Rabi oscillations direct excitons, excitons with a hybridized electron wave function. An off-resonant detection technique based phonon-mediated state transfer allows for spectrally filtered under resonant...
We present Purcell-enhanced ($F_\mathrm{P} > 25$) semiconductor InAs quantum dot radiative lifetimes of $T_1 < 30~\mathrm{ps}$, enabled by deterministic hybrid circular Bragg gratings (hCBGs). investigate the benefits these short T1 times on two-photon indistinguishability for quasi-resonant and strictly resonant excitation, observe visibilities $\geq96\%$ at 12.5 ns time delay consecutively emitted photons. The strongly decay enable a high degree elevated temperatures up to 30 K, moreover,...
Quantum dot molecules (QDMs) are one of the few quantum light sources that promise deterministic generation one- and two-dimensional photonic graph states. The proposed protocols rely on coherent excitation tunnel-coupled spatially indirect exciton Here, we demonstrate power-dependent Rabi oscillations direct excitons, excitons with a hybridized electron wave function. An off-resonant detection technique based phonon-mediated state transfer allows for spectrally filtered under resonant...
Self-assembled optically active quantum dot molecules (QDMs) allow the creation of protected qubits via singlet-triplet spin states. The qubit energy splitting these states is defined by tunnel coupling strength and is, therefore, determined potential landscape thus fixed during growth. Applying an in-plane magnetic field increases confinement hybridized wave functions within dots, leading to a decrease strength. We achieve tuning $(53.4\pm1.7)$ %. ability fine-tune this essential for...
Semiconductor quantum dot molecules are considered as promising candidates for technological applications due to their wide tunability of optical properties and coverage different energy scales associated with charge spin physics. While previous works have studied the tunnel-coupling excitonic complexes shared by two dots conventional spectroscopy, we here report on first demonstration a coherently controlled inter-dot focusing coherence optically active trion transitions. We employ...
Degradation during start-up and shut-down (SUSD) of proton exchange membrane (PEM) fuel cells is investigated both experimentally numerically. In order to understand spatial degradation, the local cell voltage electrochemical surface area (ECSA) SUSD are measured using a segmented cell. Novel phenomena such as undegraded inlet segments gradual rise in resting potential at start test hence observed. To further interpret experimental data, an advanced model developed, which accurately...
We report on a prototype quantum photonic integrated circuit consisting of two dots deterministically into nanobeam cavities at the input ports 2x2 multimode interference beam-splitter featuring high single-photon purity and indistinguishability.
The realization of efficient quantum light sources relies on the integration self-assembled dots (QDs) into photonic nanostructures with high spatial positioning accuracy. In this work, we present a comprehensive investigation QD position accuracy, obtained using two marker-based techniques, photoluminescence (PL) and cathodoluminescence (CL) imaging, as well marker-free in-situ electron beam lithography (in-situ EBL) technique. We employ four PL imaging configurations three different image...
We report on the epitaxial growth, theoretical modeling, and structural as well optical investigation of multi-layer, site-controlled quantum dots fabricated using buried stressor method. This advanced growth technique utilizes strain from a partially oxidized AlAs layer to induce site-selective nucleation InGaAs dots. By implementing strain-induced spectral nano-engineering, we achieve separation in emission energy by about 150 meV positioned non-positioned local increase emitter density...